151 vignette for making spatial grids (#154)

* add vignette for making a spatial grid file

* update spatial grid vignette

* update information on zone ID information in making spatial grid vignette

* updated spatial grid vignette

* update final line in description file

DESCRIPTION

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 RoxygenNote: 7.3.1
 LazyData: true
 Config/testthat/edition: 3
-GithubSHA1: d65b9a34f1ca5d334fbb9b749da6acc382df8f61
+GithubSHA1: d65b9a34f1ca5d334fbb9b749da6acc382df8f61

vignettes/making_a_spatial_grid.Rmd

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+---
+title: "Making a spatial grid file"
+author: "Paul Carvalho"
+date: "`r Sys.Date()`"
+output:
+  rmarkdown::html_vignette:
+    fig_width: 6
+    fig_height: 4
+vignette: >
+  %\VignetteIndexEntry{Making a spatial grid}
+  %\VignetteEngine{knitr::rmarkdown}
+  %\VignetteEncoding{UTF-8}
+editor_options: 
+  markdown: 
+    wrap: 72
+---
+
+
+```{r setup, include=FALSE}
+knitr::opts_chunk$set(echo = TRUE)
+```
+
+## Load packages
+```{r packages}
+library(sf) 
+library(ggplot2)
+```
+
+## Create a spatial grid
+
+```{r grid, echo=TRUE}
+# Define the bounding box of the grid
+# latitude: 10 to 40 degrees N
+# longitude: -170 to -130 degrees W
+bbox <- c(xmin = -170, xmax = -130, ymin = 10, ymax = 40)
+
+# Define the size of each grid cell
+# 5 degree x 5 degree grid
+cell_size <- c(x = 5, y = 5)
+
+# Create the grid
+grid_sf <- st_make_grid(
+  st_as_sfc(st_bbox(bbox)),  # Bounding box for the grid
+  cellsize = cell_size,       # Size of each cell
+  what = "polygons"           # Grid cells as polygons
+)
+
+# Convert to an sf object
+grid_sf <- st_sf(geometry = grid_sf, crs = 4326)
+```
+If you have a spatial data table loaded as a dataframe, use the [st_as_sf()](https://www.rdocumentation.org/packages/sf/versions/1.0-16/topics/st_as_sf) function from the [sf](https://www.rdocumentation.org/packages/sf/versions/1.0-16) package to convert the dataframe to an sf object.
+
+### Add zone ID variable to the spatial object
+
+The zone ID variable in the primary data table can be reassigned to match the zone IDs in the spatial grid object based on the lat/lon of fishing location in the primary data table.
+
+```{r zoneID, echo=TRUE}
+# Assign zone ID variable
+# Here the ID is just a sequence from 1 to the number of grids in the spatial object
+grid_sf$zoneID <- seq(1:length(grid_sf$geometry))
+```
+
+### Plot
+```{r plot_grid, echo=TRUE}
+# Plot just the spatial grid object using the ggplot2 package
+ggplot() +
+  geom_sf(data = grid_sf)
+
+# Add a world map layer to the plot
+base_map <- ggplot2::map_data("world",
+                              xlim = c(bbox["xmin"], bbox["xmax"]),
+                              ylim = c(bbox["ymin"], bbox["ymax"]))
+
+base_map <- FishSET::dat_to_sf(base_map, lon = "long", lat = "lat", id = "group",
+                        cast = "POLYGON", multi = TRUE, crs = 4326)
+
+ggplot() +
+  geom_sf(data = base_map) +
+  geom_sf(data = grid_sf, fill=NA) +
+  theme_minimal() +
+  labs(title = "5x5 Degree Spatial Grid")
+```
+
+### Save spatial grid
+```{r save_grid, echo=TRUE}
+# Uncomment the code below to save the spatial grid as an RDS file to be used in FishSET
+# Note: the second input should include the filepath and filename to be saved. See help documentation for saveRDS().
+
+# saveRDS(grid_sf, "fiveByFiveGrid.rds")
+```