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Code Projects

+ +
+ +
+
+ + + + +
+ +
+

Code Projects#

+
    +

  • modular design

    • +

  • minimal viable product

    • +

  • test-driven development

    • +

  • rapid prototyping

    • +

  • project organization

    • +

  • refactoring

    • +

  • code review

    • +
+
+

Modular Design#

+
+Modular design, like modular programming, is the approach of designing and building things as independent modules. +
+
+

Minimal Viable Product#

+
+A 'minimal viable product' is a product that contains the minimum amount of implemented features to use the code product - no more, no less.
+
+

Test-Driven Development#

+
+Writing the tests as soon as you have a plan & before you've written the code. +
+
+

Rapid Prototyping#

+
+Rapid prototyping is an approach for developing things in which you work on minimal prototypes and iterate on them quickly. +
+

Some rapid prototyping examples#

+
    +

  • Chatbot: start and end a chat

    • +

  • Data Analysis: read a dataset in, make a basic plot

    • +

  • Car Inventory: object with method that adds a car to the Inventory

    • +

  • Artificial Agents: simple bot moves around randomly

    • +
+
+
+
+

Project Organization#

+
    +

  • Notebooks: good for interactive development

    +
      +

    • For when seeing the inputs and outputs of code running needs to be seen start to finish

      • +

    • file ends in .ipynb

      • +
    +
    • +

  • Modules: for storing mature Python code, that you can import

    +
      +

    • you don’t use the functions in there, just define them

      • +

    • file ends in .py

      • +
    +
    • +

  • Scripts: a Python file for executing a particular task

    +
      +

    • this takes an input and does something start to finish

      • +

    • file ends in .py

      • +
    +
    • +
+
+

Project Workflow#

+

Typical project workflow:

+
    +

  • Develop plan and write tests

    • +

  • Develop code interactively in a Jupyter notebook/text editor

    • +

  • As functions & classes become mature, move them to Python files that you then import

    +
      +

    • As you do so, go back through them to check for code style, add documentation, and run your code tests

      • +
    +
    • +

  • At the end of a project, (maybe) write a standalone script that runs the project

    • +
+
+

Project Notes#

+
    +

  1. Design and write tests

    2. +

  2. Write some code

    3. +

  3. Test to make sure it works

    4. +

  4. Check code style (naming, spacing, etc.)

    5. +

  5. Add documentation

    6. +

  6. Move to module (if necessary)

    7. +

  7. Run all tests

    8. +
+
+
+
+

Project Design#

+
    +

  • Idea: atbash encryption: return the capitalized, reverse alphabetical letter for each character in the input string

    • +

  • Design:

    +
      +

    • atbash_encrypt() : take input string and retrun atbash encrypted string

      +
        +

      • inputs: input_string

        • +

      • returns: atbash_string

        • +
      +
      • +

    • atbash_decrypt() : take encrypted string and decrypt using atbash

      +
        +

      • inputs: atbash_string

        • +

      • returns: decrypted_string

        • +
      +
      • +

    • atbash_wrapper() : does either of the above, as specified with input parameter

      +
        +

      • inputs: input_string, method (either ‘encrypt’ or ‘decrypt’, default: ‘encrypt’)

        • +

      • returns output_string

        • +
      +
      • +
    +
    • +
+
+
+

Adding Unit Tests#

+
+
+
# from atbash import *
+
+# def test_atbash_encrypt():
+#     assert callable(atbash_encrypt)
+#     assert isinstance(atbash_encrypt('hello'), str)
+#     assert atbash_encrypt('HELLO') == 'SVOOL'
+#     assert atbash_encrypt('hello') == 'SVOOL'
+    
+# def test_atbash_decrypt():
+#     assert callable(atbash_decrypt)
+#     assert isinstance(atbash_decrypt('hello'), str)
+#     assert atbash_decrypt('SVOOL') == 'HELLO'
+#     assert atbash_decrypt('svool') == 'HELLO'
+
+# def test_atbash_wrapper():
+#     assert callable(atbash_wrapper)
+#     assert isinstance(atbash_wrapper('hello', method='encrypt'), str)
+#     assert atbash_wrapper('hello', method='encrypt') == 'SVOOL'
+#     assert atbash_wrapper('HELLO', method='encrypt') == 'SVOOL'
+#     assert atbash_wrapper('SVOOL', method='decrypt') == 'HELLO'
+#     assert atbash_wrapper('svool', method='decrypt') == 'HELLO'
+#     assert atbash_wrapper('svool', method='blargh') == "method should be either 'decrypt' or 'encrypt'"
+
+
+
+
+

…move to test file

+

…will uncomment as I write the code/functions

+
+
+

Writing Code#

+
+

atbash_encrypt#

+
+
+
def atbash_encrypt(input_string):
+    alpha = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+    reverse_alpha = 'ZYXWVUTSRQPONMLKJIHGFEDCBA'
+
+    atbash_string = ''
+
+    for char in input_string:
+        char = char.upper()
+        if char in alpha:
+            position = alpha.find(char)
+            atbash_string += reverse_alpha[position]
+        else:
+            atbash_string = None
+            break
+        
+    return atbash_string
+
+
+
+
+
+
+
# smoke test
+atbash_encrypt('Hello')
+
+
+
+
+
+
+
+

Moving to a module…#

+

Now that we have our working function, we should move it to a module file

+
    +

  • don’t forget to import your new module at the top of the test file

    • +
+

Note on imports: If you want to be able to use modules (imports) within a module/script, be sure to import it at the top. This applies to test files as well.

+
+
+
!pytest test_atbash.py
+
+
+
+
+
+

atbash_decrypt#

+
+
+
# reminder: consider code style! 
+def atbash_decrypt(atbash_string):    
+    ALPHA='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+    REVERSEALPHA='ZYXWVUTSRQPONMLKJIHGFEDCBA'
+    atbash_string=atbash_string.upper()
+    decrypted_string=''
+    for l in atbash_string:
+        if l in REVERSEALPHA:
+            letterindex=REVERSEALPHA.find(l)
+            decrypted_string=decrypted_string+ALPHA[letterindex]
+        else: decrypted_string=decrypted_string+l
+    return decrypted_string
+
+
+
+
+
+
+
# smoke test
+atbash_decrypt('SVOOL')
+
+
+
+
+
+
+
!pytest test_atbash.py
+
+
+
+
+
+
+

atbash_wrapper#

+
+
+
def atbash_wrapper(input_string, method='encrypt'):
+    
+    if method == 'encrypt':
+        output_string = atbash_encrypt(input_string)
+    elif method == 'decrypt':
+        output_string = atbash_decrypt(input_string)
+    else:
+        output_string = "method should be either 'decrypt' or 'encrypt'"
+    
+    return output_string
+
+
+
+
+
+
+
# smoke test
+atbash_wrapper('hello', 'encrypt')
+
+
+
+
+
+
+
!pytest test_atbash.py
+
+
+
+
+
+
+
+

Documentation#

+
    +

  • Code in final project/exam requires:

    +
      +

    • numpy-style docstrings

      • +

    • code comments

      • +
    +
    • +
+
+
+

Putting it all together#

+
+
+
from atbash import atbash_wrapper
+
+
+
+
+
+
+
atbash_wrapper('hello')
+
+
+
+
+
+
+
atbash_wrapper('svool', method='decrypt')
+
+
+
+
+
+
+
atbash_wrapper('hello', method='blargh')
+
+
+
+
+
+
+

Refactoring#

+
+Refactoring is the process of restructuring existing computer code, without changing its external behaviour. +

Think of this as restructuring and final edits on your essay.

+

Nesting Functions - If you have a whole bunch of functions, if statements, and for/while loops together within a single function, you probably want (need?) to refactor.

+

Clean functions accomplish a single task!

+

DRY: Don’t Repeat Yourself

+
+

Refactoring Example: Chatbot#

+
+
+
import random 
+
+def have_a_chat():
+    """Main function to run our chatbot."""
+    
+    chat = True
+
+    while chat:
+
+        # Get a message from the user
+        msg = input('INPUT :\t')
+        out_msg = None
+        
+        # Check if the input is a question
+        input_string = msg
+        if '?' in input_string:
+            question = True
+        else:
+            question = False
+
+        # Check for an end msg 
+        if 'quit' in input_string:
+            out_msg = 'Bye!'
+            chat = False
+            
+        # If we don't have an output yet, but the input was a question, 
+        # return msg related to it being a question
+        if not out_msg and question:
+            out_msg = "I'm too shy to answer questions. What do you want to talk about?"
+
+        # Catch-all to say something if msg not caught & processed so far
+        if not out_msg:
+            out_msg = random.choice(['Good.', 'Okay', 'Huh?', 'Yeah!', 'Thanks!'])
+
+        print('OUTPUT:', out_msg)
+
+
+
+
+
+
+
have_a_chat()  
+
+
+
+
+
+
+

Refactored Example: Chatbot#

+

What this function does:

+
    +

  1. takes an input

    2. +

  2. checks if input is a question

    3. +

  3. checks if input is supposed to end the chat

    4. +

  4. return appropriate response if question, end chat, or other

    5. +
+

That’s four different things! Functions should do a single thing…

+
+
+
def get_input():
+    """ask user for an input message"""
+    
+    msg = input('INPUT :\t')   
+    out_msg = None
+    
+    return msg, out_msg
+
+
+
+
+
+
+
def is_question(input_string):
+    """determine if input from user is a question"""
+    
+    if '?' in input_string:
+        output = True
+    else:
+        output = False
+    
+    return output
+
+
+
+
+
+
+
def end_chat(input_list):
+    """identify if user says 'quit' in input and end chat"""
+    
+    if 'quit' in input_list:
+        output = 'Bye'
+        chat = False
+    else:
+        output = None
+        chat = True
+        
+    return output, chat
+
+
+
+
+
+
+
def return_message(out_msg, question):
+    """generic responses for the chatbot to return"""
+        
+    # If we don't have an output yet, but the input was a question, 
+    # return msg related to it being a question
+    if not out_msg and question:
+        out_msg = "I'm too shy to answer questions. What do you want to talk about?"
+
+    # Catch-all to say something if msg not caught & processed so far
+    if not out_msg:
+        out_msg = random.choice(['Good.', 'Okay', 'Huh?', 'Yeah!', 'Thanks!'])
+        
+    return out_msg
+
+
+
+
+
+
+
def have_a_chat():
+    """Main function to run our chatbot."""
+    
+    chat = True
+
+    while chat:
+
+        # Get input message from the user
+        msg, out_msg = get_input()
+        
+        # Check if the input is a question
+        question = is_question(msg)
+         
+        # Check for an end msg 
+        out_msg, chat = end_chat(msg)
+       
+        # specify what to return 
+        out_msg = return_message(out_msg = out_msg, question = question)
+        
+        print('OUTPUT:', out_msg)
+
+
+
+
+
+
+
have_a_chat()  
+
+
+
+
+
+
+
+
+

Code Review#

+
+Code review is a process for systematically reviewing someone else's code. +
+
+ + + + +
+ + + + + + + + +
+ + + +
+ + +
+
+ Contents +
+
+ +
+ + +
+
+ +
+ +
+ +

+By Shannon Ellis, Jason Fleischer, and Tom Donoghue +

+ +
+ +
+ + +

+ + © Copyright 2023. +
+ +

+ +
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+ +
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+ + +