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<!DOCTYPE html>
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<title> 5 Tutorial: Data visualization with ggplot | Data journalism</title>
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<meta name="author" content="Lara Kobilke, IfKW, Ludwig-Maximilians-Universität München" />
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<li><a href="./">Data Journalism</a></li>
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<li class="chapter" data-level="" data-path="index.html"><a href="index.html"><i class="fa fa-check"></i>General information on the course</a>
<ul>
<li class="chapter" data-level="" data-path="index.html"><a href="index.html#what-can-i-learn-from-this-tutorial"><i class="fa fa-check"></i>What can I learn from this tutorial?</a></li>
<li class="chapter" data-level="" data-path="index.html"><a href="index.html#what-can-i-do-if-i-have-a-question"><i class="fa fa-check"></i>What can I do if I have a question?</a></li>
<li class="chapter" data-level="" data-path="index.html"><a href="index.html#what-can-i-do-if-i-have-problems-with-my-r-code"><i class="fa fa-check"></i>What can I do if I have problems with my R code?</a></li>
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<li class="chapter" data-level="1" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html"><i class="fa fa-check"></i><b>1</b> Tutorial: Installing & Understanding R/R Studio</a>
<ul>
<li class="chapter" data-level="1.1" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#installing-r"><i class="fa fa-check"></i><b>1.1</b> Installing R</a></li>
<li class="chapter" data-level="1.2" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#installing-r-studio"><i class="fa fa-check"></i><b>1.2</b> Installing R Studio</a></li>
<li class="chapter" data-level="1.3" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#updating-r-and-r-studio"><i class="fa fa-check"></i><b>1.3</b> Updating R and R Studio</a>
<ul>
<li class="chapter" data-level="1.3.1" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#on-windows"><i class="fa fa-check"></i><b>1.3.1</b> On Windows</a></li>
<li class="chapter" data-level="1.3.2" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#on-mac"><i class="fa fa-check"></i><b>1.3.2</b> On MAC</a></li>
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<li class="chapter" data-level="1.4" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#how-does-r-work"><i class="fa fa-check"></i><b>1.4</b> How does R work?</a></li>
<li class="chapter" data-level="1.5" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#why-should-i-use-r"><i class="fa fa-check"></i><b>1.5</b> Why should I use R?</a></li>
<li class="chapter" data-level="1.6" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#how-does-r-studio-work"><i class="fa fa-check"></i><b>1.6</b> How does R Studio work?</a>
<ul>
<li class="chapter" data-level="1.6.1" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#source-writing-your-own-code"><i class="fa fa-check"></i><b>1.6.1</b> Source: Writing your own code</a></li>
<li class="chapter" data-level="1.6.2" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#console-printing-results"><i class="fa fa-check"></i><b>1.6.2</b> Console: Printing results</a></li>
<li class="chapter" data-level="1.6.3" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#environment-overview-of-objects"><i class="fa fa-check"></i><b>1.6.3</b> Environment: Overview of objects</a></li>
<li class="chapter" data-level="1.6.4" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#plotshelppackages-do-everything-else"><i class="fa fa-check"></i><b>1.6.4</b> Plots/Help/Packages: Do everything else</a></li>
</ul></li>
<li class="chapter" data-level="1.7" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#packages"><i class="fa fa-check"></i><b>1.7</b> Packages</a>
<ul>
<li class="chapter" data-level="1.7.1" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#installing-packages"><i class="fa fa-check"></i><b>1.7.1</b> Installing packages</a></li>
<li class="chapter" data-level="1.7.2" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#activating-packages"><i class="fa fa-check"></i><b>1.7.2</b> Activating packages</a></li>
<li class="chapter" data-level="1.7.3" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#getting-information-about-packages"><i class="fa fa-check"></i><b>1.7.3</b> Getting information about packages</a></li>
</ul></li>
<li class="chapter" data-level="1.8" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#take-aways"><i class="fa fa-check"></i><b>1.8</b> Take-Aways</a></li>
<li class="chapter" data-level="1.9" data-path="tutorial-installing-understanding-rr-studio.html"><a href="tutorial-installing-understanding-rr-studio.html#additional-tutorials"><i class="fa fa-check"></i><b>1.9</b> Additional tutorials</a></li>
</ul></li>
<li class="chapter" data-level="2" data-path="tutorial-using-r-as-a-calculator.html"><a href="tutorial-using-r-as-a-calculator.html"><i class="fa fa-check"></i><b>2</b> Tutorial: Using R as a calculator</a>
<ul>
<li class="chapter" data-level="2.1" data-path="tutorial-using-r-as-a-calculator.html"><a href="tutorial-using-r-as-a-calculator.html#using-variables-for-calculation"><i class="fa fa-check"></i><b>2.1</b> Using variables for calculation</a></li>
<li class="chapter" data-level="2.2" data-path="tutorial-using-r-as-a-calculator.html"><a href="tutorial-using-r-as-a-calculator.html#using-vectors-for-calculation"><i class="fa fa-check"></i><b>2.2</b> Using vectors for calculation</a></li>
<li class="chapter" data-level="2.3" data-path="tutorial-using-r-as-a-calculator.html"><a href="tutorial-using-r-as-a-calculator.html#selecting-values-from-a-vector"><i class="fa fa-check"></i><b>2.3</b> Selecting values from a vector</a></li>
<li class="chapter" data-level="2.4" data-path="tutorial-using-r-as-a-calculator.html"><a href="tutorial-using-r-as-a-calculator.html#take-aways-1"><i class="fa fa-check"></i><b>2.4</b> Take-Aways</a></li>
<li class="chapter" data-level="2.5" data-path="tutorial-using-r-as-a-calculator.html"><a href="tutorial-using-r-as-a-calculator.html#additional-tutorials-1"><i class="fa fa-check"></i><b>2.5</b> Additional tutorials</a></li>
</ul></li>
<li class="chapter" data-level="3" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html"><i class="fa fa-check"></i><b>3</b> Tutorial: Working with data (files)</a>
<ul>
<li class="chapter" data-level="3.1" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#defining-your-working-directory"><i class="fa fa-check"></i><b>3.1</b> Defining your working directory</a>
<ul>
<li class="chapter" data-level="3.1.1" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#optional-setting-the-working-directory-on-a-remote-desktop"><i class="fa fa-check"></i><b>3.1.1</b> Optional: Setting the working directory on a remote desktop</a></li>
</ul></li>
<li class="chapter" data-level="3.2" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#import-data-from-your-working-directory"><i class="fa fa-check"></i><b>3.2</b> Import data from your working directory</a></li>
<li class="chapter" data-level="3.3" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#subsetting-variables-columns-in-data-frames"><i class="fa fa-check"></i><b>3.3</b> Subsetting variables / columns in data frames</a></li>
<li class="chapter" data-level="3.4" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#subsetting-observations-rows-in-data-frames"><i class="fa fa-check"></i><b>3.4</b> Subsetting observations / rows in data frames</a></li>
<li class="chapter" data-level="3.5" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#subsetting-values-cells-in-data-frames"><i class="fa fa-check"></i><b>3.5</b> Subsetting values / cells in data frames</a></li>
<li class="chapter" data-level="3.6" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#subsetting-data-with-conditions"><i class="fa fa-check"></i><b>3.6</b> Subsetting data with conditions</a></li>
<li class="chapter" data-level="3.7" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#take-aways-2"><i class="fa fa-check"></i><b>3.7</b> Take-Aways</a></li>
<li class="chapter" data-level="3.8" data-path="tutorial-working-with-data-files.html"><a href="tutorial-working-with-data-files.html#additional-tutorials-2"><i class="fa fa-check"></i><b>3.8</b> Additional tutorials</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="exercise-1.html"><a href="exercise-1.html"><i class="fa fa-check"></i>Exercise 1</a>
<ul>
<li class="chapter" data-level="" data-path="exercise-1.html"><a href="exercise-1.html#task-1"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="exercise-1.html"><a href="exercise-1.html#task-2"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="exercise-1.html"><a href="exercise-1.html#task-3"><i class="fa fa-check"></i>Task 3</a></li>
<li class="chapter" data-level="" data-path="exercise-1.html"><a href="exercise-1.html#task-4"><i class="fa fa-check"></i>Task 4</a></li>
<li class="chapter" data-level="" data-path="exercise-1.html"><a href="exercise-1.html#task-5"><i class="fa fa-check"></i>Task 5</a></li>
<li class="chapter" data-level="" data-path="exercise-1.html"><a href="exercise-1.html#task-6"><i class="fa fa-check"></i>Task 6</a></li>
</ul></li>
<li class="chapter" data-level="4" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html"><i class="fa fa-check"></i><b>4</b> Tutorial: Data management with tidyverse</a>
<ul>
<li class="chapter" data-level="4.1" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#why-not-stick-with-base-r"><i class="fa fa-check"></i><b>4.1</b> Why not stick with Base R?</a></li>
<li class="chapter" data-level="4.2" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#tidyverse-packages"><i class="fa fa-check"></i><b>4.2</b> Tidyverse packages</a></li>
<li class="chapter" data-level="4.3" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#tidy-data"><i class="fa fa-check"></i><b>4.3</b> Tidy data</a></li>
<li class="chapter" data-level="4.4" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#the-pipe-operator"><i class="fa fa-check"></i><b>4.4</b> The pipe operator</a></li>
<li class="chapter" data-level="4.5" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#data-transformation-with-dplyr"><i class="fa fa-check"></i><b>4.5</b> Data transformation with dplyr</a>
<ul>
<li class="chapter" data-level="4.5.1" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#select"><i class="fa fa-check"></i><b>4.5.1</b> select()</a></li>
<li class="chapter" data-level="4.5.2" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#filter"><i class="fa fa-check"></i><b>4.5.2</b> filter()</a></li>
<li class="chapter" data-level="4.5.3" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#arrange"><i class="fa fa-check"></i><b>4.5.3</b> arrange()</a></li>
<li class="chapter" data-level="4.5.4" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#mutate"><i class="fa fa-check"></i><b>4.5.4</b> mutate()</a></li>
<li class="chapter" data-level="4.5.5" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#summarize-group_by"><i class="fa fa-check"></i><b>4.5.5</b> summarize() [+ group_by()]</a></li>
<li class="chapter" data-level="4.5.6" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#chaining-functions-in-a-pipe"><i class="fa fa-check"></i><b>4.5.6</b> Chaining functions in a pipe</a></li>
</ul></li>
<li class="chapter" data-level="4.6" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#take-aways-3"><i class="fa fa-check"></i><b>4.6</b> Take-Aways</a></li>
<li class="chapter" data-level="4.7" data-path="tutorial-data-management-with-tidyverse.html"><a href="tutorial-data-management-with-tidyverse.html#additional-tutorials-3"><i class="fa fa-check"></i><b>4.7</b> Additional tutorials</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="exercise-2-test-your-knowledge.html"><a href="exercise-2-test-your-knowledge.html"><i class="fa fa-check"></i>Exercise 2: Test your knowledge</a>
<ul>
<li class="chapter" data-level="" data-path="exercise-2-test-your-knowledge.html"><a href="exercise-2-test-your-knowledge.html#task-1-1"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="exercise-2-test-your-knowledge.html"><a href="exercise-2-test-your-knowledge.html#task-2-1"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="exercise-2-test-your-knowledge.html"><a href="exercise-2-test-your-knowledge.html#task-3-1"><i class="fa fa-check"></i>Task 3</a></li>
<li class="chapter" data-level="" data-path="exercise-2-test-your-knowledge.html"><a href="exercise-2-test-your-knowledge.html#task-4-1"><i class="fa fa-check"></i>Task 4</a></li>
<li class="chapter" data-level="" data-path="exercise-2-test-your-knowledge.html"><a href="exercise-2-test-your-knowledge.html#task-5-1"><i class="fa fa-check"></i>Task 5</a></li>
<li class="chapter" data-level="" data-path="exercise-2-test-your-knowledge.html"><a href="exercise-2-test-your-knowledge.html#task-6-1"><i class="fa fa-check"></i>Task 6</a></li>
<li class="chapter" data-level="" data-path="exercise-2-test-your-knowledge.html"><a href="exercise-2-test-your-knowledge.html#task-7"><i class="fa fa-check"></i>Task 7</a></li>
</ul></li>
<li class="chapter" data-level="5" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html"><i class="fa fa-check"></i><b>5</b> Tutorial: Data visualization with ggplot</a>
<ul>
<li class="chapter" data-level="5.1" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#why-not-stick-with-base-r-1"><i class="fa fa-check"></i><b>5.1</b> Why not stick with Base R?</a></li>
<li class="chapter" data-level="5.2" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#components-of-a-ggplot-graph"><i class="fa fa-check"></i><b>5.2</b> Components of a ggplot graph</a></li>
<li class="chapter" data-level="5.3" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#installing-activating-ggplot"><i class="fa fa-check"></i><b>5.3</b> Installing & activating ggplot</a></li>
<li class="chapter" data-level="5.4" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#building-your-first-plot"><i class="fa fa-check"></i><b>5.4</b> Building your first plot</a>
<ul>
<li class="chapter" data-level="5.4.1" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#data"><i class="fa fa-check"></i><b>5.4.1</b> Data</a></li>
<li class="chapter" data-level="5.4.2" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#aesthetics"><i class="fa fa-check"></i><b>5.4.2</b> Aesthetics</a></li>
<li class="chapter" data-level="5.4.3" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#geometrics"><i class="fa fa-check"></i><b>5.4.3</b> Geometrics</a></li>
<li class="chapter" data-level="5.4.4" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#scales"><i class="fa fa-check"></i><b>5.4.4</b> Scales</a></li>
<li class="chapter" data-level="5.4.5" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#themes"><i class="fa fa-check"></i><b>5.4.5</b> Themes</a></li>
<li class="chapter" data-level="5.4.6" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#labs"><i class="fa fa-check"></i><b>5.4.6</b> Labs</a></li>
<li class="chapter" data-level="5.4.7" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#facets"><i class="fa fa-check"></i><b>5.4.7</b> Facets</a></li>
<li class="chapter" data-level="5.4.8" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#saving-graphs"><i class="fa fa-check"></i><b>5.4.8</b> Saving graphs</a></li>
</ul></li>
<li class="chapter" data-level="5.5" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#other-common-plot-types"><i class="fa fa-check"></i><b>5.5</b> Other common plot types</a>
<ul>
<li class="chapter" data-level="5.5.1" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#bar-plots"><i class="fa fa-check"></i><b>5.5.1</b> bar plots</a></li>
<li class="chapter" data-level="5.5.2" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#box-plots"><i class="fa fa-check"></i><b>5.5.2</b> box plots</a></li>
</ul></li>
<li class="chapter" data-level="5.6" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#take-aways-4"><i class="fa fa-check"></i><b>5.6</b> Take Aways</a></li>
<li class="chapter" data-level="5.7" data-path="tutorial-data-visualization-with-ggplot.html"><a href="tutorial-data-visualization-with-ggplot.html#additional-tutorials-4"><i class="fa fa-check"></i><b>5.7</b> Additional tutorials</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="exercise-3-test-your-knowledge.html"><a href="exercise-3-test-your-knowledge.html"><i class="fa fa-check"></i>Exercise 3: Test your knowledge</a>
<ul>
<li class="chapter" data-level="" data-path="exercise-3-test-your-knowledge.html"><a href="exercise-3-test-your-knowledge.html#task-1-2"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="exercise-3-test-your-knowledge.html"><a href="exercise-3-test-your-knowledge.html#task-2-2"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="exercise-3-test-your-knowledge.html"><a href="exercise-3-test-your-knowledge.html#task-3-2"><i class="fa fa-check"></i>Task 3</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html"><i class="fa fa-check"></i>Exercise 4: Test your knowledge</a>
<ul>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html#task-1-3"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html#task-2-3"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html#task-3-3"><i class="fa fa-check"></i>Task 3</a></li>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html#task-4-2"><i class="fa fa-check"></i>Task 4</a></li>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html#task-5-2"><i class="fa fa-check"></i>Task 5</a></li>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html#task-6-2"><i class="fa fa-check"></i>Task 6</a></li>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html#task-7-1"><i class="fa fa-check"></i>Task 7</a></li>
<li class="chapter" data-level="" data-path="exercise-4-test-your-knowledge.html"><a href="exercise-4-test-your-knowledge.html#task-8"><i class="fa fa-check"></i>Task 8</a></li>
</ul></li>
<li class="chapter" data-level="6" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html"><i class="fa fa-check"></i><b>6</b> Tutorial: Text manipulation with stringr</a>
<ul>
<li class="chapter" data-level="6.1" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#whats-stringr"><i class="fa fa-check"></i><b>6.1</b> What’s stringr?</a></li>
<li class="chapter" data-level="6.2" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#working-with-strings"><i class="fa fa-check"></i><b>6.2</b> Working with strings</a></li>
<li class="chapter" data-level="6.3" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#working-with-string-patterns"><i class="fa fa-check"></i><b>6.3</b> Working with string patterns</a></li>
<li class="chapter" data-level="6.4" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#working-with-regular-expressions"><i class="fa fa-check"></i><b>6.4</b> Working with regular expressions</a>
<ul>
<li class="chapter" data-level="6.4.1" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#anchors-alternates-and-quantifiers"><i class="fa fa-check"></i><b>6.4.1</b> Anchors, alternates, and quantifiers</a></li>
<li class="chapter" data-level="6.4.2" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#look-arounds-and-groups"><i class="fa fa-check"></i><b>6.4.2</b> Look arounds and groups</a></li>
<li class="chapter" data-level="6.4.3" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#match-specific-types-of-characters"><i class="fa fa-check"></i><b>6.4.3</b> Match specific types of characters</a></li>
</ul></li>
<li class="chapter" data-level="6.5" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#take-aways-5"><i class="fa fa-check"></i><b>6.5</b> Take-Aways</a></li>
<li class="chapter" data-level="6.6" data-path="tutorial-text-manipulation-with-stringr.html"><a href="tutorial-text-manipulation-with-stringr.html#additional-tutorials-5"><i class="fa fa-check"></i><b>6.6</b> Additional tutorials</a></li>
</ul></li>
<li class="chapter" data-level="7" data-path="exercise-5-test-your-knowledge.html"><a href="exercise-5-test-your-knowledge.html"><i class="fa fa-check"></i><b>7</b> Exercise 5: Test your knowledge</a>
<ul>
<li class="chapter" data-level="7.1" data-path="exercise-5-test-your-knowledge.html"><a href="exercise-5-test-your-knowledge.html#task-1-4"><i class="fa fa-check"></i><b>7.1</b> Task 1</a></li>
<li class="chapter" data-level="7.2" data-path="exercise-5-test-your-knowledge.html"><a href="exercise-5-test-your-knowledge.html#task-2-4"><i class="fa fa-check"></i><b>7.2</b> Task 2</a></li>
<li class="chapter" data-level="7.3" data-path="exercise-5-test-your-knowledge.html"><a href="exercise-5-test-your-knowledge.html#task-3-4"><i class="fa fa-check"></i><b>7.3</b> Task 3</a></li>
<li class="chapter" data-level="7.4" data-path="exercise-5-test-your-knowledge.html"><a href="exercise-5-test-your-knowledge.html#task-4-3"><i class="fa fa-check"></i><b>7.4</b> Task 4</a></li>
</ul></li>
<li class="chapter" data-level="8" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html"><i class="fa fa-check"></i><b>8</b> Tidy text analysis</a>
<ul>
<li class="chapter" data-level="8.1" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#what-is-tidy-text"><i class="fa fa-check"></i><b>8.1</b> What is tidy text?</a></li>
<li class="chapter" data-level="8.2" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#preprocessing-real-world-data"><i class="fa fa-check"></i><b>8.2</b> Preprocessing real-world data</a>
<ul>
<li class="chapter" data-level="8.2.1" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#tokenization"><i class="fa fa-check"></i><b>8.2.1</b> Tokenization</a></li>
<li class="chapter" data-level="" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#practice-tokenization"><i class="fa fa-check"></i>Practice: Tokenization</a></li>
<li class="chapter" data-level="8.2.2" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#stop-word-removal"><i class="fa fa-check"></i><b>8.2.2</b> Stop word removal</a></li>
<li class="chapter" data-level="" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#practice-stop-word-removal"><i class="fa fa-check"></i>Practice: Stop word removal</a></li>
<li class="chapter" data-level="8.2.3" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#lemmatizing-stemming"><i class="fa fa-check"></i><b>8.2.3</b> Lemmatizing & stemming</a></li>
<li class="chapter" data-level="" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#practice-lemmatizing-stemming"><i class="fa fa-check"></i>Practice: Lemmatizing & stemming</a></li>
<li class="chapter" data-level="8.2.4" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#pruning"><i class="fa fa-check"></i><b>8.2.4</b> Pruning</a></li>
<li class="chapter" data-level="" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#practice-pruning"><i class="fa fa-check"></i>Practice: Pruning</a></li>
</ul></li>
<li class="chapter" data-level="8.3" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#topic-modeling"><i class="fa fa-check"></i><b>8.3</b> Topic modeling</a>
<ul>
<li class="chapter" data-level="8.3.1" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#first-steps-create-a-sparse-matrix"><i class="fa fa-check"></i><b>8.3.1</b> First steps: Create a sparse matrix</a></li>
<li class="chapter" data-level="8.3.2" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#first-steps-create-a-date-covariate"><i class="fa fa-check"></i><b>8.3.2</b> First steps: Create a date covariate</a></li>
<li class="chapter" data-level="8.3.3" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#model-estimation-number-of-topics"><i class="fa fa-check"></i><b>8.3.3</b> Model estimation: Number of topics</a></li>
<li class="chapter" data-level="" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#practice-model-estimation"><i class="fa fa-check"></i>Practice: Model estimation</a></li>
<li class="chapter" data-level="8.3.4" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#inspect-the-topics"><i class="fa fa-check"></i><b>8.3.4</b> Inspect the topics</a></li>
<li class="chapter" data-level="" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#practice-inspect-models"><i class="fa fa-check"></i>Practice: Inspect models</a></li>
<li class="chapter" data-level="8.3.5" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#find-the-best-value-for-k"><i class="fa fa-check"></i><b>8.3.5</b> Find the best value for K</a></li>
</ul></li>
<li class="chapter" data-level="8.4" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#sentiment-analysis"><i class="fa fa-check"></i><b>8.4</b> Sentiment analysis</a>
<ul>
<li class="chapter" data-level="8.4.1" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#sentiment-over-time"><i class="fa fa-check"></i><b>8.4.1</b> Sentiment over time</a></li>
<li class="chapter" data-level="" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#practice-sentiment-over-time"><i class="fa fa-check"></i>Practice: Sentiment over time</a></li>
<li class="chapter" data-level="8.4.2" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#sentiment-over-time-periods"><i class="fa fa-check"></i><b>8.4.2</b> Sentiment over time periods</a></li>
<li class="chapter" data-level="8.4.3" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#sentiment-of-individual-users"><i class="fa fa-check"></i><b>8.4.3</b> Sentiment of individual users</a></li>
</ul></li>
<li class="chapter" data-level="8.5" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#take-aways-6"><i class="fa fa-check"></i><b>8.5</b> Take-Aways</a></li>
<li class="chapter" data-level="8.6" data-path="tidy-text-analysis.html"><a href="tidy-text-analysis.html#additional-tutorials-6"><i class="fa fa-check"></i><b>8.6</b> Additional tutorials</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html"><i class="fa fa-check"></i>Solutions</a>
<ul>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#solutions-for-exercise-1"><i class="fa fa-check"></i>Solutions for Exercise 1</a>
<ul>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-1-5"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-2-5"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-3-5"><i class="fa fa-check"></i>Task 3</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-4-4"><i class="fa fa-check"></i>Task 4</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-5-3"><i class="fa fa-check"></i>Task 5</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-6-3"><i class="fa fa-check"></i>Task 6</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#solutions-for-exercise-2"><i class="fa fa-check"></i>Solutions for Exercise 2</a>
<ul>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-1-6"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-2-6"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-3-6"><i class="fa fa-check"></i>Task 3</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-4-5"><i class="fa fa-check"></i>Task 4</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-5-4"><i class="fa fa-check"></i>Task 5</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-6-4"><i class="fa fa-check"></i>Task 6</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-7-2"><i class="fa fa-check"></i>Task 7</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#solutions-for-exercise-3"><i class="fa fa-check"></i>Solutions for Exercise 3</a>
<ul>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-1-7"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-2-7"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-3-7"><i class="fa fa-check"></i>Task 3</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#solutions-for-exercise-4"><i class="fa fa-check"></i>Solutions for Exercise 4</a>
<ul>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-1-8"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-2-8"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-3-8"><i class="fa fa-check"></i>Task 3</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-4-6"><i class="fa fa-check"></i>Task 4</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-5-5"><i class="fa fa-check"></i>Task 5</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-6-5"><i class="fa fa-check"></i>Task 6</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-7-3"><i class="fa fa-check"></i>Task 7</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-8-1"><i class="fa fa-check"></i>Task 8</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#solutions-for-exercise-5"><i class="fa fa-check"></i>Solutions for Exercise 5</a>
<ul>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-1-9"><i class="fa fa-check"></i>Task 1</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-2-9"><i class="fa fa-check"></i>Task 2</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-3-9"><i class="fa fa-check"></i>Task 3</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-4-7"><i class="fa fa-check"></i>Task 4</a></li>
</ul></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#solutions-for-exercise-6"><i class="fa fa-check"></i>Solutions for Exercise 6</a>
<ul>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-1-tokenization"><i class="fa fa-check"></i>Task 1: Tokenization</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-2-stop-word-removal"><i class="fa fa-check"></i>Task 2: Stop word removal</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-3-lemmatizing-stemming"><i class="fa fa-check"></i>Task 3: Lemmatizing & stemming</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-4-pruning"><i class="fa fa-check"></i>Task 4: Pruning</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-5-model-estimation"><i class="fa fa-check"></i>Task 5: Model estimation</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-6-inspect-models"><i class="fa fa-check"></i>Task 6: Inspect models</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-7-sentiment-over-time"><i class="fa fa-check"></i>Task 7: Sentiment over time</a></li>
<li class="chapter" data-level="" data-path="solutions.html"><a href="solutions.html#task-8-sentiment-over-time-periods"><i class="fa fa-check"></i>Task 8: Sentiment over time periods</a></li>
</ul></li>
</ul></li>
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<li><a href="https://github.com/LKobilke/data-journalism" target="blank">Published with bookdown</a></li>
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<div id="tutorial-data-visualization-with-ggplot" class="section level1 hasAnchor" number="5">
<h1><span class="header-section-number"> 5</span> Tutorial: Data visualization with ggplot<a href="tutorial-data-visualization-with-ggplot.html#tutorial-data-visualization-with-ggplot" class="anchor-section" aria-label="Anchor link to header"></a></h1>
<p>After working through Tutorial 5, you’ll…</p>
<ul>
<li>know what each graphical component of a ggplot graph contributes to
the final visualization</li>
<li>understand the <code>grammer of graphics</code> (or simply: the ggplot2 syntax)
to combine graphical components</li>
<li>know how to make your own data visualizations using <code>ggplot2</code></li>
</ul>
<div id="why-not-stick-with-base-r-1" class="section level2 hasAnchor" number="5.1">
<h2><span class="header-section-number">5.1</span> Why not stick with Base R?<a href="tutorial-data-visualization-with-ggplot.html#why-not-stick-with-base-r-1" class="anchor-section" aria-label="Anchor link to header"></a></h2>
<p>The <code>ggplot2</code> package, i.e. the data visualization package of
<code>tidyverse</code>, has become <strong>the</strong> R package for data visualization. While
<code>Base R</code> can be used to visualize data, the <code>ggplot2</code> package makes data
visualization so much easier that I recommend starting with <code>ggplot2</code>
right away and skipping data visualization in <code>Base R</code> altogether.</p>
<p>The <code>gg</code> in <code>ggplot2</code> stands for <code>grammar of graphics</code>, which means that
we can describe each component of a graph layer by layer and component
by component. You only have to provide <code>ggplot()</code> with a source object
(i.e. data) and specify what variables it should map to the aesthetical
attributes (color, shape, size) of certain geometric objects (points,
lines, bars) – and <code>ggplot</code> will take care of the rest! The inventor of
<code>ggplot2</code>, Hadley Wickham, describes the benefits of <code>ggplot2</code> like
this:</p>
<blockquote>
<p>“In order to unlock the full power of ggplot2, <strong>you’ll need to master
the underlying grammar</strong>. By understanding the grammar, and how its
components fit together, you can create a wider range of
visualizations, combine multiple sources of data, and customise to
your heart’s content… The grammar makes it easier for you to
<strong>iteratively update a plot</strong>, changing a single feature at a time.
The grammar is also useful because it suggests the high-level aspects
of a plot that can be changed, giving you a framework to think about
graphics, and hopefully shortening the distance from mind to paper. It
also <strong>encourages the use of graphics customised to a particular
problem</strong>, rather than relying on specific chart types.” (<a href="https://ggplot2-book.org/mastery.html">Wickham et
al., 2021, no page; bold words
inserted</a>)</p>
</blockquote>
<p>Just as <code>dplyr</code> simplifies data manipulation, <code>ggplot2</code> simplifies data
visualization. In addition, <code>ggplot2</code> and <code>dplyr</code> work hand in hand: You
can prepare your data selection and manipulation with <code>dplyr</code> and pipe
it directly into <code>ggplot</code> to turn your transformed data into a beautiful
graph.</p>
<p>With only a few lines of code, you can produce graphs like this one:</p>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-69-1.png" width="120%" /></p>
<p>This is the code. Right now, it might still look a bit overwhelming to
you, but once you’ve understood the grammar of graphics, it really is a
just a small jigsaw puzzle. Moreover, you don’t usually start with
graphs that are this complicated, but with basic scatter or bar plots.</p>
<div class="sourceCode" id="cb144"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb144-1"><a href="tutorial-data-visualization-with-ggplot.html#cb144-1" aria-hidden="true" tabindex="-1"></a><span class="fu">library</span>(ggplot2)</span>
<span id="cb144-2"><a href="tutorial-data-visualization-with-ggplot.html#cb144-2" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb144-3"><a href="tutorial-data-visualization-with-ggplot.html#cb144-3" aria-hidden="true" tabindex="-1"></a>plot <span class="ot"><-</span> starwars_data <span class="sc">%>%</span></span>
<span id="cb144-4"><a href="tutorial-data-visualization-with-ggplot.html#cb144-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">filter</span>(species <span class="sc">==</span> <span class="st">"Human"</span> <span class="sc">|</span> species <span class="sc">==</span> <span class="st">"Droid"</span>) <span class="sc">%>%</span></span>
<span id="cb144-5"><a href="tutorial-data-visualization-with-ggplot.html#cb144-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size =</span> birth_year, <span class="at">fill =</span> species)) <span class="sc">+</span></span>
<span id="cb144-6"><a href="tutorial-data-visualization-with-ggplot.html#cb144-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span></span>
<span id="cb144-7"><a href="tutorial-data-visualization-with-ggplot.html#cb144-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb144-8"><a href="tutorial-data-visualization-with-ggplot.html#cb144-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb144-9"><a href="tutorial-data-visualization-with-ggplot.html#cb144-9" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span></span>
<span id="cb144-10"><a href="tutorial-data-visualization-with-ggplot.html#cb144-10" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb144-11"><a href="tutorial-data-visualization-with-ggplot.html#cb144-11" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="sc">+</span></span>
<span id="cb144-12"><a href="tutorial-data-visualization-with-ggplot.html#cb144-12" aria-hidden="true" tabindex="-1"></a> ggrepel<span class="sc">::</span><span class="fu">geom_text_repel</span>(<span class="fu">aes</span>(<span class="at">label =</span> name), <span class="at">size =</span> <span class="fl">2.3</span>) <span class="sc">+</span></span>
<span id="cb144-13"><a href="tutorial-data-visualization-with-ggplot.html#cb144-13" aria-hidden="true" tabindex="-1"></a> <span class="fu">theme_bw</span>() <span class="sc">+</span></span>
<span id="cb144-14"><a href="tutorial-data-visualization-with-ggplot.html#cb144-14" aria-hidden="true" tabindex="-1"></a> <span class="fu">labs</span>(<span class="at">title =</span> <span class="st">"Mass vs. height of humans and droids in Star Wars"</span>,</span>
<span id="cb144-15"><a href="tutorial-data-visualization-with-ggplot.html#cb144-15" aria-hidden="true" tabindex="-1"></a> <span class="at">x =</span> <span class="st">"Height (cm)"</span>, <span class="at">y =</span> <span class="st">"Weight (kg)"</span>) <span class="sc">+</span></span>
<span id="cb144-16"><a href="tutorial-data-visualization-with-ggplot.html#cb144-16" aria-hidden="true" tabindex="-1"></a> <span class="fu">facet_wrap</span>(<span class="sc">~</span>species)</span></code></pre></div>
<p>To visit the official documentation of <code>ggplot2</code>:
1. type <code>?ggplot2</code> in your console
2. visit the <a href="https://www.rdocumentation.org/packages/ggplot2/versions/3.3.5">ggplot documentation</a>
3. visit the <a href="https://ggplot2.tidyverse.org/">ggplot homepage of the tidyverse</a></p>
</div>
<div id="components-of-a-ggplot-graph" class="section level2 hasAnchor" number="5.2">
<h2><span class="header-section-number">5.2</span> Components of a ggplot graph<a href="tutorial-data-visualization-with-ggplot.html#components-of-a-ggplot-graph" class="anchor-section" aria-label="Anchor link to header"></a></h2>
<p>As mentioned before, the main idea behind <code>ggplot</code> is to generate a
statistical plot by combining layers that represent geometric objects
(e.g. points and lines). By linking data to the aesthetic features of
these geometric objects (e.g. colors, size, transparency), the aesthetic
properties of the geometric objects may be controlled. In the words of
Wickham:</p>
<blockquote>
<p>“A graphic maps the <strong>data</strong> to the <strong>aesthetic</strong> attributes (colour,
shape, size) of <strong>geometric</strong> objects (points, lines, bars).” <a href="https://ggplot2-book.org/introduction.html">Wickham
et al., 2021, no page; bold words
inserted</a></p>
</blockquote>
<table>
<colgroup>
<col width="100%" />
</colgroup>
<tbody>
<tr class="odd">
<td><em>Image: The logic of adding layer by layer in ggplot (<a href="https://bookdown.org/sunboklee/introduction_to_r/week2-data-visualization-i.html">Source: R @ Ewah 2020</a>):</em></td>
</tr>
<tr class="even">
<td><img src="images/Tut5_plotlayers.png" /></td>
</tr>
</tbody>
</table>
<p>The <strong>necessary</strong> components of a <code>ggplot</code> graph are:</p>
<ol style="list-style-type: decimal">
<li>Source object / <code>data</code>: The data that you would like to visualize.</li>
<li>Geometries <code>geom_</code>: Geom options allow you to specify what geometric
objects will represent the data (i.e. points, bars, lines, and many
more).</li>
<li>Aesthetics <code>aes()</code>: Aesthetics allows you to map variables to the x-
and y-axis and to the aesthetics of those geometric objects (i.e.
position, color, size, shape, linetype, and transparency).</li>
</ol>
<p>The <strong>complementary, but not necessary</strong> components of a <code>ggplot</code> graph
are:</p>
<ol start="4" style="list-style-type: decimal">
<li>Scales <code>scale_</code>: Scale options allow you to fine-tune the mapping
from the variables to the aesthetics. You can fine-tune axis limits,
tick breaks, grid lines, or any other axis/geometric object
transformations that depend on the range of a specific scale.</li>
<li>Statistical transformations <code>stat_</code>: Allows you to produce
statistical summaries of the data for visualization (i.e. means and
standard deviations, fitted curves, and many more).</li>
<li>Coordinate system <code>coord_</code>: Allows you to change the appearance of
your coordinate system (i.e. flip the coordinates to turn horizontal
bar chart into a vertical one).</li>
<li>Position: to adjust overlapping objects, e.g. jittering, stacking or
dodging.</li>
<li>Facets <code>facet_</code>: Allows you to divide your plot into multiple
subplots.</li>
<li>Visual themes <code>theme()</code>: Allows you to specify the visual basics of
a plot, such as background, default typeface, sizes, and colors.</li>
<li>Axis labels <code>labs()</code>: Allows you to change the plot’s main title and
the axis labels.</li>
</ol>
</div>
<div id="installing-activating-ggplot" class="section level2 hasAnchor" number="5.3">
<h2><span class="header-section-number">5.3</span> Installing & activating ggplot<a href="tutorial-data-visualization-with-ggplot.html#installing-activating-ggplot" class="anchor-section" aria-label="Anchor link to header"></a></h2>
<p>You can always activate <code>ggplot2</code> by activating the meta-package
<code>tidyverse</code>:</p>
<div class="sourceCode" id="cb145"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb145-1"><a href="tutorial-data-visualization-with-ggplot.html#cb145-1" aria-hidden="true" tabindex="-1"></a><span class="fu">library</span>(tidyverse)</span></code></pre></div>
<p>If for some reason you do not want to activate the whole <code>tidyverse</code>,
you should install <code>ggplot2</code> and activate this package separately:</p>
<div class="sourceCode" id="cb146"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb146-1"><a href="tutorial-data-visualization-with-ggplot.html#cb146-1" aria-hidden="true" tabindex="-1"></a><span class="fu">install.packages</span>(<span class="st">"ggplot2"</span>) <span class="co"># install the package (only on the first time)</span></span></code></pre></div>
<div class="sourceCode" id="cb147"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb147-1"><a href="tutorial-data-visualization-with-ggplot.html#cb147-1" aria-hidden="true" tabindex="-1"></a><span class="fu">library</span>(ggplot2) <span class="co"># active the package</span></span></code></pre></div>
</div>
<div id="building-your-first-plot" class="section level2 hasAnchor" number="5.4">
<h2><span class="header-section-number">5.4</span> Building your first plot<a href="tutorial-data-visualization-with-ggplot.html#building-your-first-plot" class="anchor-section" aria-label="Anchor link to header"></a></h2>
<p>In the next sections, you will create your very first plot – layer by
layer. We will look at some of the most important components that you
will regularly add to graphs and you will learn how to make use of them.</p>
<div id="data" class="section level3 hasAnchor" number="5.4.1">
<h3><span class="header-section-number">5.4.1</span> Data<a href="tutorial-data-visualization-with-ggplot.html#data" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>Obviously, you need data to perform data visualization. Therefore, our
first step is to load the <em>starwars data</em>, but let’s keep only humans
and droids for now. To this end, assign your transformed data to a new
data frame called <em>human_droid_data</em>.</p>
<div class="sourceCode" id="cb148"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb148-1"><a href="tutorial-data-visualization-with-ggplot.html#cb148-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="ot"><-</span> dplyr<span class="sc">::</span>starwars <span class="sc">%>%</span></span>
<span id="cb148-2"><a href="tutorial-data-visualization-with-ggplot.html#cb148-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">filter</span>(species <span class="sc">==</span> <span class="st">"Human"</span> <span class="sc">|</span> species <span class="sc">==</span> <span class="st">"Droid"</span>)</span></code></pre></div>
<p>The function <code>ggplot()</code> can only create a plot if we explicitly tell the
function what data to use, so this graphical component is <strong>necessary</strong>.
Using our <code>dplyr</code> skills, let’s use the <em>human_droid_data</em> as our source
object and apply the <code>ggplot()</code> function to it by using a pipe (i.e.
%>%).</p>
<div class="sourceCode" id="cb149"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb149-1"><a href="tutorial-data-visualization-with-ggplot.html#cb149-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span> </span>
<span id="cb149-2"><a href="tutorial-data-visualization-with-ggplot.html#cb149-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>()</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-75-1.png" width="672" /></p>
<p>The <code>ggplot()</code> function creates a blank canvas (i.e. first layer). We
now have to draw on it.</p>
</div>
<div id="aesthetics" class="section level3 hasAnchor" number="5.4.2">
<h3><span class="header-section-number">5.4.2</span> Aesthetics<a href="tutorial-data-visualization-with-ggplot.html#aesthetics" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>To draw on this blank canvas, we must at least tell the <code>ggplot()</code>
function which variables to assign to the x- and y-axis by using the
<code>aes()</code> function. Thus, the Aesthetics graph component is also
<strong>necessary</strong> in every single plot.</p>
<div class="sourceCode" id="cb150"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb150-1"><a href="tutorial-data-visualization-with-ggplot.html#cb150-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span> </span>
<span id="cb150-2"><a href="tutorial-data-visualization-with-ggplot.html#cb150-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass))</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-76-1.png" width="672" /></p>
<p>The <code>aes()</code> function allows you to specify the following arguments (and
many more, as you will learn over time):</p>
<ul>
<li><strong>x</strong>: the variable that should be mapped to the x axis</li>
<li><strong>y</strong>: the variable that should be mapped to the y</li>
<li><strong>size</strong>: the variable that should be used for determining the
<em>size</em> of a geometric object</li>
<li><strong>fill</strong>: the variable that should be used for <em>filling</em> a geometric
object with a specific color</li>
<li><strong>color</strong>: the variable that should be used for <em>outlining</em> a
geometric object with a specific color</li>
</ul>
</div>
<div id="geometrics" class="section level3 hasAnchor" number="5.4.3">
<h3><span class="header-section-number">5.4.3</span> Geometrics<a href="tutorial-data-visualization-with-ggplot.html#geometrics" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>Finally, we can turn to the last <strong>necessary</strong> component of any ggplot
graph: the geometric objects that fill your canvas. The choice of these
geometric objects determines what kind of chart you create.</p>
<p>The <code>geom_</code> component of the <code>ggplot()</code> function allows you to create
the following chart types (and many more, as you will learn over time):</p>
<ul>
<li><strong>geom_bar()</strong>: to create a bar chart</li>
<li><strong>geom_histogram</strong>: to create a histogram</li>
<li><strong>geom_line()</strong>: to create a line graph</li>
<li><strong>geom_point()</strong>: to create a scatter or bubble plot</li>
<li><strong>geom_boxplot()</strong>: to create a box plot</li>
</ul>
<p>Now let’s add the data points (x,y) with <em>geom_point()</em> to our canvas to
make it a scatter plot:</p>
<div class="sourceCode" id="cb151"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb151-1"><a href="tutorial-data-visualization-with-ggplot.html#cb151-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span> </span>
<span id="cb151-2"><a href="tutorial-data-visualization-with-ggplot.html#cb151-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass)) <span class="sc">+</span></span>
<span id="cb151-3"><a href="tutorial-data-visualization-with-ggplot.html#cb151-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>()</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-77-1.png" width="672" /></p>
<p>That’s a scatter plot for sure! And you only needed three <strong>necessary</strong>
components to create it:</p>
<ol style="list-style-type: decimal">
<li>data (i.e. a source object),</li>
<li>aesthetics <code>aes()</code>,</li>
<li>and geometric objects <code>geom_</code>.</li>
</ol>
</div>
<div id="scales" class="section level3 hasAnchor" number="5.4.4">
<h3><span class="header-section-number">5.4.4</span> Scales<a href="tutorial-data-visualization-with-ggplot.html#scales" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>A scale is a mapping from data to the final values that computers can
use to actually show the aesthetics. In this sense, a scale
<strong>regulates</strong> the aesthetic mapping of variables to aesthetics.
Providing a <code>scale_</code> is not <strong>necessary</strong> to create a graph, but it
allows you to fine-tune aesthetic mappings to customize your graph.
<code>scale_</code> is very powerful and over time, you will learn about a lot of
things that you can customize with it. For now, we will only focus on a
few of these.</p>
<p>We will use <code>scale_</code> to :</p>
<ul>
<li>change the limits and ticks of the x and y axis</li>
<li>change how a third variable (besides x and y) is mapped to the
aesthetics of our geometric object</li>
</ul>
<p>First, we will use <code>scale_</code> to modify the x and the y axis by providing
the graph with new axis limits.</p>
<div class="sourceCode" id="cb152"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb152-1"><a href="tutorial-data-visualization-with-ggplot.html#cb152-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb152-2"><a href="tutorial-data-visualization-with-ggplot.html#cb152-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass)) <span class="sc">+</span></span>
<span id="cb152-3"><a href="tutorial-data-visualization-with-ggplot.html#cb152-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>() <span class="sc">+</span></span>
<span id="cb152-4"><a href="tutorial-data-visualization-with-ggplot.html#cb152-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> <span class="co"># modify the y axis limits</span></span>
<span id="cb152-5"><a href="tutorial-data-visualization-with-ggplot.html#cb152-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="co"># modify the x axis limits</span></span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-78-1.png" width="672" /></p>
<p>Second, we’ll add more ticks to make the graph better readable.</p>
<div class="sourceCode" id="cb153"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb153-1"><a href="tutorial-data-visualization-with-ggplot.html#cb153-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb153-2"><a href="tutorial-data-visualization-with-ggplot.html#cb153-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass)) <span class="sc">+</span></span>
<span id="cb153-3"><a href="tutorial-data-visualization-with-ggplot.html#cb153-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>() <span class="sc">+</span></span>
<span id="cb153-4"><a href="tutorial-data-visualization-with-ggplot.html#cb153-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb153-5"><a href="tutorial-data-visualization-with-ggplot.html#cb153-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb153-6"><a href="tutorial-data-visualization-with-ggplot.html#cb153-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> <span class="co"># choose where the ticks of the y axis appear</span></span>
<span id="cb153-7"><a href="tutorial-data-visualization-with-ggplot.html#cb153-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="co"># choose where the ticks of the x axis appear</span></span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-79-1.png" width="672" /></p>
<p>Until now, we have used <code>scale_</code> to transform only the axes. But we can
also use it to change the mapping of variables to geometric objects. To
demonstrate this, we now add another variable to our graph, namely the
age (<em>birth_year</em>) of the humanoid and droid Star Wars characters. Let’s
map age to our data points (i.e. <code>geom_point()</code>) so that larger bubbles
reflect older age.</p>
<div class="sourceCode" id="cb154"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb154-1"><a href="tutorial-data-visualization-with-ggplot.html#cb154-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb154-2"><a href="tutorial-data-visualization-with-ggplot.html#cb154-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year)) <span class="sc">+</span> <span class="co"># map birth_year (age) to the size of the following geometric objects</span></span>
<span id="cb154-3"><a href="tutorial-data-visualization-with-ggplot.html#cb154-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>() <span class="sc">+</span></span>
<span id="cb154-4"><a href="tutorial-data-visualization-with-ggplot.html#cb154-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb154-5"><a href="tutorial-data-visualization-with-ggplot.html#cb154-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb154-6"><a href="tutorial-data-visualization-with-ggplot.html#cb154-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb154-7"><a href="tutorial-data-visualization-with-ggplot.html#cb154-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) </span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-80-1.png" width="672" /></p>
<p>Personally, I feel like these bubbles could use a little bit of
rescaling to make age differences stand out more. In addition, you could
get a nicer title for the size legend than “birth_year”. Let’s try that.</p>
<div class="sourceCode" id="cb155"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb155-1"><a href="tutorial-data-visualization-with-ggplot.html#cb155-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb155-2"><a href="tutorial-data-visualization-with-ggplot.html#cb155-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year)) <span class="sc">+</span></span>
<span id="cb155-3"><a href="tutorial-data-visualization-with-ggplot.html#cb155-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>() <span class="sc">+</span></span>
<span id="cb155-4"><a href="tutorial-data-visualization-with-ggplot.html#cb155-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb155-5"><a href="tutorial-data-visualization-with-ggplot.html#cb155-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb155-6"><a href="tutorial-data-visualization-with-ggplot.html#cb155-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb155-7"><a href="tutorial-data-visualization-with-ggplot.html#cb155-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb155-8"><a href="tutorial-data-visualization-with-ggplot.html#cb155-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="co"># sets the bubbles' size in a range between 1 and 11 and renames the respective legend title to "age"</span></span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-81-1.png" width="672" /></p>
<p>Perfect! The legend spells “age” and age differences seem a bit more
obvious now. Unfortunately, some data points are now overlapping.</p>
<p>I think this is a good time to introduce you to the differences between
using <code>scale_</code> and adding aesthetics to the <code>geom_</code> objects directly.
While the former allows you to change the mapping from <strong>variables</strong> to
the aesthetics of geometric objects, the latter one allows you to
provide a <strong>constant</strong>. This means that the aesthetic mapping does not
depend on the values of a variable, but is set to a single default
value. To demonstrate this and fix the overlap of our bubbles, we change
the transparency value of the bubbles so that they become transparent.
Note that all the values given are constants, which means that they do
not depend on a third variable like <em>birth_year</em>.</p>
<div class="sourceCode" id="cb156"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb156-1"><a href="tutorial-data-visualization-with-ggplot.html#cb156-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb156-2"><a href="tutorial-data-visualization-with-ggplot.html#cb156-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year)) <span class="sc">+</span></span>
<span id="cb156-3"><a href="tutorial-data-visualization-with-ggplot.html#cb156-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">fill =</span> <span class="st">"black"</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span> <span class="co"># shape = 21 is creating bubbles that have a border (i.e. outline), fill = "black" fills the bubble with black ink, alpha = 0.25 to make the bubbles` black ink 25% transparent and color = "black" to make the border (i.e. outline) pitch black</span></span>
<span id="cb156-4"><a href="tutorial-data-visualization-with-ggplot.html#cb156-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb156-5"><a href="tutorial-data-visualization-with-ggplot.html#cb156-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb156-6"><a href="tutorial-data-visualization-with-ggplot.html#cb156-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb156-7"><a href="tutorial-data-visualization-with-ggplot.html#cb156-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb156-8"><a href="tutorial-data-visualization-with-ggplot.html#cb156-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>)</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-82-1.png" width="672" /></p>
<p>This looks way more readable. I think we are ready to move on to
<a href="tutorial-data-visualization-with-ggplot.html#themes">Themes</a>.</p>
</div>
<div id="themes" class="section level3 hasAnchor" number="5.4.5">
<h3><span class="header-section-number">5.4.5</span> Themes<a href="tutorial-data-visualization-with-ggplot.html#themes" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>Just like <code>scale_</code>, <code>theme_</code>is an optional ggplot component, i.e. <strong>not
necessary</strong>. Themes are visually appealing presets for charts, e.g.,
they influence whether grid lines are visible or whether certain color
palettes are applied to the data. By using themes you can make your
graphs more beautiful and give them a consistent style without any
effort, which is especially useful for longer texts like theses. To
familiarize yourself with the various options, take a look at this
<a href="https://ggplot2.tidyverse.org/reference/ggtheme.html">overview of all ggplot2
themes</a>.</p>
<p>If you don’t like grid lines, for example, <em>theme_classic()</em> might be to
your taste:</p>
<div class="sourceCode" id="cb157"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb157-1"><a href="tutorial-data-visualization-with-ggplot.html#cb157-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb157-2"><a href="tutorial-data-visualization-with-ggplot.html#cb157-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year)) <span class="sc">+</span></span>
<span id="cb157-3"><a href="tutorial-data-visualization-with-ggplot.html#cb157-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">fill =</span> <span class="st">"black"</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span></span>
<span id="cb157-4"><a href="tutorial-data-visualization-with-ggplot.html#cb157-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb157-5"><a href="tutorial-data-visualization-with-ggplot.html#cb157-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb157-6"><a href="tutorial-data-visualization-with-ggplot.html#cb157-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb157-7"><a href="tutorial-data-visualization-with-ggplot.html#cb157-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb157-8"><a href="tutorial-data-visualization-with-ggplot.html#cb157-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="sc">+</span></span>
<span id="cb157-9"><a href="tutorial-data-visualization-with-ggplot.html#cb157-9" aria-hidden="true" tabindex="-1"></a> <span class="fu">theme_classic</span>()</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-83-1.png" width="672" /></p>
<p>Personally, I really enjoy the <em>theme_bw()</em> (black-and-white theme). So
let’s apply it to our graph:</p>
<div class="sourceCode" id="cb158"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb158-1"><a href="tutorial-data-visualization-with-ggplot.html#cb158-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb158-2"><a href="tutorial-data-visualization-with-ggplot.html#cb158-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year)) <span class="sc">+</span></span>
<span id="cb158-3"><a href="tutorial-data-visualization-with-ggplot.html#cb158-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">fill =</span> <span class="st">"black"</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span></span>
<span id="cb158-4"><a href="tutorial-data-visualization-with-ggplot.html#cb158-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb158-5"><a href="tutorial-data-visualization-with-ggplot.html#cb158-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb158-6"><a href="tutorial-data-visualization-with-ggplot.html#cb158-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb158-7"><a href="tutorial-data-visualization-with-ggplot.html#cb158-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb158-8"><a href="tutorial-data-visualization-with-ggplot.html#cb158-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="sc">+</span></span>
<span id="cb158-9"><a href="tutorial-data-visualization-with-ggplot.html#cb158-9" aria-hidden="true" tabindex="-1"></a> <span class="fu">theme_bw</span>()</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-84-1.png" width="672" /></p>
</div>
<div id="labs" class="section level3 hasAnchor" number="5.4.6">
<h3><span class="header-section-number">5.4.6</span> Labs<a href="tutorial-data-visualization-with-ggplot.html#labs" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>Again, <code>labs()</code> is not a <strong>necessary</strong>, but an optional component of
your graph. Using the <code>labs()</code> function allows you to set a main title
for your plot and to change the labels of the x and y axis.</p>
<p>Let’s try it:</p>
<div class="sourceCode" id="cb159"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb159-1"><a href="tutorial-data-visualization-with-ggplot.html#cb159-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb159-2"><a href="tutorial-data-visualization-with-ggplot.html#cb159-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year)) <span class="sc">+</span></span>
<span id="cb159-3"><a href="tutorial-data-visualization-with-ggplot.html#cb159-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">fill =</span> <span class="st">"black"</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span></span>
<span id="cb159-4"><a href="tutorial-data-visualization-with-ggplot.html#cb159-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb159-5"><a href="tutorial-data-visualization-with-ggplot.html#cb159-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb159-6"><a href="tutorial-data-visualization-with-ggplot.html#cb159-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb159-7"><a href="tutorial-data-visualization-with-ggplot.html#cb159-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb159-8"><a href="tutorial-data-visualization-with-ggplot.html#cb159-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="sc">+</span></span>
<span id="cb159-9"><a href="tutorial-data-visualization-with-ggplot.html#cb159-9" aria-hidden="true" tabindex="-1"></a> <span class="fu">theme_bw</span>() <span class="sc">+</span></span>
<span id="cb159-10"><a href="tutorial-data-visualization-with-ggplot.html#cb159-10" aria-hidden="true" tabindex="-1"></a> <span class="fu">labs</span>(<span class="at">title =</span> <span class="st">"Mass vs. height of humans and droids in Star Wars"</span>,</span>
<span id="cb159-11"><a href="tutorial-data-visualization-with-ggplot.html#cb159-11" aria-hidden="true" tabindex="-1"></a> <span class="at">x =</span> <span class="st">"Height (cm)"</span>, <span class="at">y =</span> <span class="st">"Weight (kg)"</span>)</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-85-1.png" width="672" /></p>
<p>Now that we’ve added a main title, it becomes clear that we can’t really
distinguish the data points that represent humans from those that
represent droids.</p>
</div>
<div id="facets" class="section level3 hasAnchor" number="5.4.7">
<h3><span class="header-section-number">5.4.7</span> Facets<a href="tutorial-data-visualization-with-ggplot.html#facets" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>Faceting divides plot into tiny subplots, which display different
subsets of your data. Facets are an effective way to explore your data
because they allow you to rapidly detect divergent patterns in these
subsets. Of course, faceting is optional, i.e. <strong>not necessary</strong>. You
don’t need faceting if you don’t want to compare different groups within
your data.</p>
<p>The two approaches to faceting are:</p>
<ul>
<li><code>facet_wrap()</code>: uses the levels of <strong>one (or more) variable(s)</strong> to
create groups + panels for each group; useful if you have a single
categorical variable with many levels</li>
<li><code>facet_grid()</code>: produces a matrix of panels defined by <strong>two
variables</strong> which form the rows and columns</li>
</ul>
<table>
<colgroup>
<col width="100%" />
</colgroup>
<tbody>
<tr class="odd">
<td><em>Image: The logic of faceting (<a href="https://ggplot2-book.org/facet.html">Source: Wickham et al., 2021</a>):</em></td>
</tr>
<tr class="even">
<td><img src="images/Tut5_faceting.jpg" /></td>
</tr>
</tbody>
</table>
<p>Let’s use the <code>facet_wrap()</code> function to create two subplots for our two
different levels of the <em>species</em> variable: Droid and Human. You can
provide two arguments to <code>facet_wrap()</code>:</p>
<ul>
<li><code>~</code>, followed by the grouping variable</li>
<li><code>nrow</code>: the number of rows in which panels should be placed</li>
</ul>
<div class="sourceCode" id="cb160"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb160-1"><a href="tutorial-data-visualization-with-ggplot.html#cb160-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb160-2"><a href="tutorial-data-visualization-with-ggplot.html#cb160-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year)) <span class="sc">+</span></span>
<span id="cb160-3"><a href="tutorial-data-visualization-with-ggplot.html#cb160-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">fill =</span> <span class="st">"black"</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span></span>
<span id="cb160-4"><a href="tutorial-data-visualization-with-ggplot.html#cb160-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb160-5"><a href="tutorial-data-visualization-with-ggplot.html#cb160-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb160-6"><a href="tutorial-data-visualization-with-ggplot.html#cb160-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb160-7"><a href="tutorial-data-visualization-with-ggplot.html#cb160-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb160-8"><a href="tutorial-data-visualization-with-ggplot.html#cb160-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="sc">+</span></span>
<span id="cb160-9"><a href="tutorial-data-visualization-with-ggplot.html#cb160-9" aria-hidden="true" tabindex="-1"></a> <span class="fu">theme_bw</span>() <span class="sc">+</span></span>
<span id="cb160-10"><a href="tutorial-data-visualization-with-ggplot.html#cb160-10" aria-hidden="true" tabindex="-1"></a> <span class="fu">labs</span>(<span class="at">title =</span> <span class="st">"Mass vs. height of humans and droids in Star Wars"</span>,</span>
<span id="cb160-11"><a href="tutorial-data-visualization-with-ggplot.html#cb160-11" aria-hidden="true" tabindex="-1"></a> <span class="at">x =</span> <span class="st">"Height (cm)"</span>, <span class="at">y =</span> <span class="st">"Weight (kg)"</span>) <span class="sc">+</span></span>
<span id="cb160-12"><a href="tutorial-data-visualization-with-ggplot.html#cb160-12" aria-hidden="true" tabindex="-1"></a> <span class="fu">facet_wrap</span>(<span class="sc">~</span>species, <span class="at">nrow=</span><span class="dv">2</span>) <span class="co"># using ~grouping_variable and nrow = 2 shows the two panels on top of each other</span></span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-86-1.png" width="672" /></p>
<p>Great, finally we can distinguish the data points representing humans
from those representing droids! On the left side, however, the panel
with the humans looks a bit empty. Maybe we should put them next to each
other.</p>
<div class="sourceCode" id="cb161"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb161-1"><a href="tutorial-data-visualization-with-ggplot.html#cb161-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb161-2"><a href="tutorial-data-visualization-with-ggplot.html#cb161-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year)) <span class="sc">+</span></span>
<span id="cb161-3"><a href="tutorial-data-visualization-with-ggplot.html#cb161-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">fill =</span> <span class="st">"black"</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span></span>
<span id="cb161-4"><a href="tutorial-data-visualization-with-ggplot.html#cb161-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb161-5"><a href="tutorial-data-visualization-with-ggplot.html#cb161-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb161-6"><a href="tutorial-data-visualization-with-ggplot.html#cb161-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb161-7"><a href="tutorial-data-visualization-with-ggplot.html#cb161-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb161-8"><a href="tutorial-data-visualization-with-ggplot.html#cb161-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="sc">+</span></span>
<span id="cb161-9"><a href="tutorial-data-visualization-with-ggplot.html#cb161-9" aria-hidden="true" tabindex="-1"></a> <span class="fu">theme_bw</span>() <span class="sc">+</span></span>
<span id="cb161-10"><a href="tutorial-data-visualization-with-ggplot.html#cb161-10" aria-hidden="true" tabindex="-1"></a> <span class="fu">labs</span>(<span class="at">title =</span> <span class="st">"Mass vs. height of humans and droids in Star Wars"</span>,</span>
<span id="cb161-11"><a href="tutorial-data-visualization-with-ggplot.html#cb161-11" aria-hidden="true" tabindex="-1"></a> <span class="at">x =</span> <span class="st">"Height (cm)"</span>, <span class="at">y =</span> <span class="st">"Weight (kg)"</span>) <span class="sc">+</span></span>
<span id="cb161-12"><a href="tutorial-data-visualization-with-ggplot.html#cb161-12" aria-hidden="true" tabindex="-1"></a> <span class="fu">facet_wrap</span>(<span class="sc">~</span>species) <span class="co"># nrow=1 is the default, so you don´t have to call it explicitly</span></span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-87-1.png" width="672" /></p>
<p>I like that!</p>
</div>
<div id="saving-graphs" class="section level3 hasAnchor" number="5.4.8">
<h3><span class="header-section-number">5.4.8</span> Saving graphs<a href="tutorial-data-visualization-with-ggplot.html#saving-graphs" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>I think it’s time that we save this plot. To finish of this
“masterpiece” (and make it less triste), let’s add some final colors
before saving. We’ll fill our bubbles with colorful ink based on the
<em>species</em> variable, so we need to add <code>fill=species</code> to the <code>aes()</code> and
remove the default black ink provided in the <code>geom_point()</code> function.</p>
<div class="sourceCode" id="cb162"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb162-1"><a href="tutorial-data-visualization-with-ggplot.html#cb162-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb162-2"><a href="tutorial-data-visualization-with-ggplot.html#cb162-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year, <span class="at">fill=</span>species)) <span class="sc">+</span></span>
<span id="cb162-3"><a href="tutorial-data-visualization-with-ggplot.html#cb162-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span></span>
<span id="cb162-4"><a href="tutorial-data-visualization-with-ggplot.html#cb162-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb162-5"><a href="tutorial-data-visualization-with-ggplot.html#cb162-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb162-6"><a href="tutorial-data-visualization-with-ggplot.html#cb162-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb162-7"><a href="tutorial-data-visualization-with-ggplot.html#cb162-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb162-8"><a href="tutorial-data-visualization-with-ggplot.html#cb162-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="sc">+</span></span>
<span id="cb162-9"><a href="tutorial-data-visualization-with-ggplot.html#cb162-9" aria-hidden="true" tabindex="-1"></a> <span class="fu">theme_bw</span>() <span class="sc">+</span></span>
<span id="cb162-10"><a href="tutorial-data-visualization-with-ggplot.html#cb162-10" aria-hidden="true" tabindex="-1"></a> <span class="fu">labs</span>(<span class="at">title =</span> <span class="st">"Mass vs. height of humans and droids in Star Wars"</span>,</span>
<span id="cb162-11"><a href="tutorial-data-visualization-with-ggplot.html#cb162-11" aria-hidden="true" tabindex="-1"></a> <span class="at">x =</span> <span class="st">"Height (cm)"</span>, <span class="at">y =</span> <span class="st">"Weight (kg)"</span>) <span class="sc">+</span></span>
<span id="cb162-12"><a href="tutorial-data-visualization-with-ggplot.html#cb162-12" aria-hidden="true" tabindex="-1"></a> <span class="fu">facet_wrap</span>(<span class="sc">~</span>species)</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-88-1.png" width="672" /></p>
<p>Congratulations! You have just managed to recreate the plot from the
beginning of this tutorial! The only thing we haven’t covered yet is the
labeling of all data points, because for that you’d need the <code>ggrepel</code>
package to not mess up the labels - and that’s not part of <code>ggplot2</code>. So
let’s skip that and save our graph.</p>
<p>To use your graph in another document, e.g. a theses written in Word,
you’ll have to export the plot first. Therefore, you must assign your
plot to a new object and call the <code>ggsave()</code> function on that object.
The plot will be saved to your <strong>working directory</strong> and formatted
according to the <strong>file extension</strong> you specified (for example: .jpeg or
.png).</p>
<div class="sourceCode" id="cb163"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb163-1"><a href="tutorial-data-visualization-with-ggplot.html#cb163-1" aria-hidden="true" tabindex="-1"></a>plot <span class="ot"><-</span> human_droid_data <span class="sc">%>%</span></span>
<span id="cb163-2"><a href="tutorial-data-visualization-with-ggplot.html#cb163-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> height, <span class="at">y =</span> mass, <span class="at">size=</span>birth_year, <span class="at">fill=</span>species)) <span class="sc">+</span></span>
<span id="cb163-3"><a href="tutorial-data-visualization-with-ggplot.html#cb163-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_point</span>(<span class="at">shape =</span> <span class="dv">21</span>, <span class="at">alpha =</span> <span class="fl">0.25</span>, <span class="at">color =</span> <span class="st">"black"</span>) <span class="sc">+</span></span>
<span id="cb163-4"><a href="tutorial-data-visualization-with-ggplot.html#cb163-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">30</span>, <span class="dv">140</span>)) <span class="sc">+</span> </span>
<span id="cb163-5"><a href="tutorial-data-visualization-with-ggplot.html#cb163-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">limits =</span> <span class="fu">c</span>(<span class="dv">90</span>, <span class="dv">210</span>)) <span class="sc">+</span></span>
<span id="cb163-6"><a href="tutorial-data-visualization-with-ggplot.html#cb163-6" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_y_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">40</span>, <span class="dv">60</span>, <span class="dv">80</span>, <span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>)) <span class="sc">+</span> </span>
<span id="cb163-7"><a href="tutorial-data-visualization-with-ggplot.html#cb163-7" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_x_continuous</span>(<span class="at">breaks =</span> <span class="fu">c</span>(<span class="dv">100</span>, <span class="dv">120</span>, <span class="dv">140</span>, <span class="dv">160</span>, <span class="dv">180</span>, <span class="dv">200</span>)) <span class="sc">+</span></span>
<span id="cb163-8"><a href="tutorial-data-visualization-with-ggplot.html#cb163-8" aria-hidden="true" tabindex="-1"></a> <span class="fu">scale_size</span>(<span class="at">range =</span> <span class="fu">c</span>(<span class="dv">1</span>, <span class="dv">11</span>), <span class="at">name =</span> <span class="st">"age"</span>) <span class="sc">+</span></span>
<span id="cb163-9"><a href="tutorial-data-visualization-with-ggplot.html#cb163-9" aria-hidden="true" tabindex="-1"></a> <span class="fu">theme_bw</span>() <span class="sc">+</span></span>
<span id="cb163-10"><a href="tutorial-data-visualization-with-ggplot.html#cb163-10" aria-hidden="true" tabindex="-1"></a> <span class="fu">labs</span>(<span class="at">title =</span> <span class="st">"Mass vs. height of humans and droids in Star Wars"</span>,</span>
<span id="cb163-11"><a href="tutorial-data-visualization-with-ggplot.html#cb163-11" aria-hidden="true" tabindex="-1"></a> <span class="at">x =</span> <span class="st">"Height (cm)"</span>, <span class="at">y =</span> <span class="st">"Weight (kg)"</span>) <span class="sc">+</span></span>
<span id="cb163-12"><a href="tutorial-data-visualization-with-ggplot.html#cb163-12" aria-hidden="true" tabindex="-1"></a> <span class="fu">facet_wrap</span>(<span class="sc">~</span>species)</span>
<span id="cb163-13"><a href="tutorial-data-visualization-with-ggplot.html#cb163-13" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb163-14"><a href="tutorial-data-visualization-with-ggplot.html#cb163-14" aria-hidden="true" tabindex="-1"></a><span class="fu">ggsave</span>(<span class="at">filename =</span> <span class="st">"mass_vs_height.jpeg"</span>, plot)</span></code></pre></div>
</div>
</div>
<div id="other-common-plot-types" class="section level2 hasAnchor" number="5.5">
<h2><span class="header-section-number">5.5</span> Other common plot types<a href="tutorial-data-visualization-with-ggplot.html#other-common-plot-types" class="anchor-section" aria-label="Anchor link to header"></a></h2>
<p>I can’t give an overview of all possible types of plots, but I can at
least touch a bit on how other common types of <code>geom_</code> behave.</p>
<div id="bar-plots" class="section level3 hasAnchor" number="5.5.1">
<h3><span class="header-section-number">5.5.1</span> bar plots<a href="tutorial-data-visualization-with-ggplot.html#bar-plots" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>Bar plots are very common. They are either (1) used to display the
frequency with which a certain factor level of a categorical variable
occurs or (2) to display relationships between a categorical variable
and a metric variable.</p>
<p>So let’s create a quick bar plot using the <em>sex</em> variable (categorical,
three factor levels) and get an overview on how many human and droidic
Star Wars characters are male, female, or do not have a sex.</p>
<div class="sourceCode" id="cb164"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb164-1"><a href="tutorial-data-visualization-with-ggplot.html#cb164-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb164-2"><a href="tutorial-data-visualization-with-ggplot.html#cb164-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> sex)) <span class="sc">+</span> <span class="co"># We only have to specify the variable that we want to get the count for (i.e. number of observations)</span></span>
<span id="cb164-3"><a href="tutorial-data-visualization-with-ggplot.html#cb164-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_bar</span>()</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-90-1.png" width="60%" /></p>
<p>Next, let’s look at the relationship between <em>sex</em> and the <em>height</em>
(metric) variable. We will produce a bar plot that displays the mean
height of each group:</p>
<div class="sourceCode" id="cb165"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb165-1"><a href="tutorial-data-visualization-with-ggplot.html#cb165-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb165-2"><a href="tutorial-data-visualization-with-ggplot.html#cb165-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> sex, <span class="at">y=</span>height)) <span class="sc">+</span> <span class="co"># Now we need to specify the variable that we want to summarize with mean statistics </span></span>
<span id="cb165-3"><a href="tutorial-data-visualization-with-ggplot.html#cb165-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_bar</span>(<span class="at">stat =</span> <span class="st">"summary"</span>, <span class="at">fun.y =</span> <span class="st">"mean"</span>) <span class="co"># apply the summary statistic of y (mean) to the geom_bars</span></span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-91-1.png" width="60%" /></p>
<p>There is an alternative writing style for those bar plots that show mean values. In this writing style, you don’t apply the summary statistics to the <em>geom_bar</em>, but you apply the <em>geom_bar</em> to the summary statistics (You might remember the optional <em>stat_</em> component of graphs from chapter <a href="tutorial-data-visualization-with-ggplot.html#components-of-a-ggplot-graph">Components of a ggplot graph</a>). While this writing style is a bit awkward, it is more flexible. So I’d recommend this code for mean bar plots:</p>
<div class="sourceCode" id="cb166"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb166-1"><a href="tutorial-data-visualization-with-ggplot.html#cb166-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb166-2"><a href="tutorial-data-visualization-with-ggplot.html#cb166-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> sex, <span class="at">y=</span>height)) <span class="sc">+</span></span>
<span id="cb166-3"><a href="tutorial-data-visualization-with-ggplot.html#cb166-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">stat_summary</span>(<span class="at">geom =</span> <span class="st">"bar"</span>, <span class="at">fun =</span> <span class="st">"mean"</span>)</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-92-1.png" width="60%" /></p>
<p>Maybe we want to sort the bars according to their mean. Let’s reorder
the factor levels manually.</p>
<div class="sourceCode" id="cb167"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb167-1"><a href="tutorial-data-visualization-with-ggplot.html#cb167-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb167-2"><a href="tutorial-data-visualization-with-ggplot.html#cb167-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">mutate</span>(<span class="at">sex =</span> <span class="fu">factor</span>(sex, <span class="at">levels =</span> <span class="fu">c</span>(<span class="st">"male"</span>, <span class="st">"female"</span>, <span class="st">"none"</span>))) <span class="sc">%>%</span> <span class="co"># This command reorders the factor levels, male = first level, female = second level, none = third level</span></span>
<span id="cb167-3"><a href="tutorial-data-visualization-with-ggplot.html#cb167-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> sex, <span class="at">y=</span>height)) <span class="sc">+</span></span>
<span id="cb167-4"><a href="tutorial-data-visualization-with-ggplot.html#cb167-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">stat_summary</span>(<span class="at">geom =</span> <span class="st">"bar"</span>, <span class="at">fun =</span> <span class="st">"mean"</span>)</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-93-1.png" width="60%" /></p>
<p>And if we would like to have a horizontal bar plot, we can use the
<code>coord_</code> component of <code>ggplot()</code> to flip the coordinates.</p>
<div class="sourceCode" id="cb168"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb168-1"><a href="tutorial-data-visualization-with-ggplot.html#cb168-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb168-2"><a href="tutorial-data-visualization-with-ggplot.html#cb168-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">mutate</span>(<span class="at">sex =</span> <span class="fu">factor</span>(sex, <span class="at">levels =</span> <span class="fu">c</span>(<span class="st">"male"</span>, <span class="st">"female"</span>, <span class="st">"none"</span>))) <span class="sc">%>%</span> </span>
<span id="cb168-3"><a href="tutorial-data-visualization-with-ggplot.html#cb168-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> sex, <span class="at">y=</span>height)) <span class="sc">+</span></span>
<span id="cb168-4"><a href="tutorial-data-visualization-with-ggplot.html#cb168-4" aria-hidden="true" tabindex="-1"></a> <span class="fu">stat_summary</span>(<span class="at">geom =</span> <span class="st">"bar"</span>, <span class="at">fun =</span> <span class="st">"mean"</span>) <span class="sc">+</span></span>
<span id="cb168-5"><a href="tutorial-data-visualization-with-ggplot.html#cb168-5" aria-hidden="true" tabindex="-1"></a> <span class="fu">coord_flip</span>()</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-94-1.png" width="60%" /></p>
</div>
<div id="box-plots" class="section level3 hasAnchor" number="5.5.2">
<h3><span class="header-section-number">5.5.2</span> box plots<a href="tutorial-data-visualization-with-ggplot.html#box-plots" class="anchor-section" aria-label="Anchor link to header"></a></h3>
<p>Box plots are a great option to summarize metric variables (by groups).
They provide you with the Five-number-summary:</p>
<ul>
<li>the sample minimum (smallest observation) – lower whisker</li>
<li>the lower quartile – lower end of the box</li>
<li>the median (the middle value) – thick black line</li>
<li>the upper quartile – upper end of the box</li>
<li>the sample maximum (largest observation) – upper whisker</li>
</ul>
<p>Let’s create box plots of the height for human and droidic Star Wars
characters who are male, female, or do not have a sex.</p>
<div class="sourceCode" id="cb169"><pre class="sourceCode r"><code class="sourceCode r"><span id="cb169-1"><a href="tutorial-data-visualization-with-ggplot.html#cb169-1" aria-hidden="true" tabindex="-1"></a>human_droid_data <span class="sc">%>%</span></span>
<span id="cb169-2"><a href="tutorial-data-visualization-with-ggplot.html#cb169-2" aria-hidden="true" tabindex="-1"></a> <span class="fu">ggplot</span>(<span class="fu">aes</span>(<span class="at">x =</span> sex, <span class="at">y=</span>height)) <span class="sc">+</span></span>
<span id="cb169-3"><a href="tutorial-data-visualization-with-ggplot.html#cb169-3" aria-hidden="true" tabindex="-1"></a> <span class="fu">geom_boxplot</span>()</span></code></pre></div>
<p><img src="Data-Journalism_files/figure-html/unnamed-chunk-95-1.png" width="60%" /></p>
<p>While box plots are a very powerful tool of data visualization, they are not understood by statistical laymen. Please don’t use them in non-scientific contexts.</p>
</div>
</div>
<div id="take-aways-4" class="section level2 hasAnchor" number="5.6">
<h2><span class="header-section-number">5.6</span> Take Aways<a href="tutorial-data-visualization-with-ggplot.html#take-aways-4" class="anchor-section" aria-label="Anchor link to header"></a></h2>
<ul>
<li><strong>graph creation</strong>: <code>ggplot()</code></li>
<li><strong>mapping variables to aesthetics</strong>:
<code>aes(x, y, color, fill, size, etc.)</code></li>
<li><strong>chart type</strong>: <code>geom_bar()</code>, <code>geom_line()</code>, <code>geom_point()</code>,
<code>geom_boxplot()</code> (for example)</li>
<li><strong>titles</strong>: <code>labs()</code></li>
<li><strong>axis limits/ticks</strong>: <code>scale_x_continuous()</code>,
<code>scale_y_continuous()</code></li>
<li><strong>mapping variables to geom size</strong>: <code>scale_size()</code></li>
<li><strong>themes</strong>: <code>theme_classic()</code>, <code>theme_light()</code>, <code>theme_bw()</code> (for
example)</li>
<li><strong>faceting</strong>: <code>facet_wrap()</code> or <code>facet_grid</code></li>
<li><strong>save images</strong>: <code>ggsave()</code></li>
</ul>
</div>
<div id="additional-tutorials-4" class="section level2 hasAnchor" number="5.7">
<h2><span class="header-section-number">5.7</span> Additional tutorials<a href="tutorial-data-visualization-with-ggplot.html#additional-tutorials-4" class="anchor-section" aria-label="Anchor link to header"></a></h2>
<p>You still have questions? The following tutorials & papers can help you
with that:</p>
<ul>
<li>Chang, W. R (2021). <em>R Graphics Codebook. Practical Recipes for
Visualizing Data.</em> <a href="https://r-graphics.org/">Link</a></li>
<li>Wickham, H., Navarro, D., & Pedersen, T. L. (2021). <em>ggplot2:
elegant graphics for data analysis.</em> Online, work-in-progress
version of the 3rd edition. <a href="https://ggplot2-book.org/">Link</a></li>
<li>Hehman, E., & Xie, S. Y. (2021). <em>Doing Better Data Visualization.
Advances in Methods and Practices in Psychological Science</em>. DOI:
10.1177/25152459211045334
<a href="https://doi.org/10.1177/25152459211045334">Link</a></li>
<li><a href="https://rc2e.com/graphics">R Codebook by J.D. Long and P. Teetor, Tutorial
10</a></li>
</ul>
<p>Now let’s see what you’ve learned so far: <a href="exercise-3-test-your-knowledge.html#exercise-3-test-your-knowledge">Exercise 3: Test your
knowledge</a>.</p>
</div>
</div>
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