By A Mystery Man Writer
layouts - Selecting different colors for touching polygons in random color ramp in QGIS? - Geographic Information Systems Stack Exchange
GIS: Keep customized colors with geom_polygon() (2 Solutions!!)
polygon - Keep customized colors with geom_polygon() - Geographic Information Systems Stack Exchange
shapefile - Using R to calculate the area of multiple polygons on a map that intersect with another overlaid polygon - Geographic Information Systems Stack Exchange
The Grammar of Graphics
England and Wales heat map in R - Data Tricks
R/ggplot2 adding an additional line/polygon to a choropleth map - Geographic Information Systems Stack Exchange
r - Customize colors in ggplot2's geom_polygon using brewer palette - Stack Overflow
Choropleth map with R and ggplot2 – the R Graph Gallery
r - Creating custom discrete color scheme for polygon attributes in ggplot2 - Geographic Information Systems Stack Exchange
coloring polygons in ggplot2 (R) - Stack Overflow
r - Creating a UK map with geom_polygon - Stack Overflow