Using ColorBrewer to assist with thematic map color selection

Choosing the right colors for classes in a thematic map can be a difficult task. The ColorBrewer website provides an interactive tool for browsing numerous color combinations. Each of the color combinations presented on the ColorBrewer website are the culmination of numerous color interpretation studies. In addition, there is a list of special color combinations suitible for audiences which may include color blind individuals.

The R package RColorBrewer adds the color brewer color combinations as well as functions for generating new combinations to R. Figure 1 demonstrates the available color combinations, as returned by the function display.brewer.all.

RColorBrewer color combinations

Figure 2: 3 colors per combination

Figure 3: 9 colors per combination

An example R session:

#load the RColorBrewer package [must be installed first with install.packages()]
library(RColorBrewer)
 
#display the "sequential" color combinations, with 3 colors per combination
#See Figure 2
display.brewer.all(n=3,type="seq",exact.n=TRUE)
title("Sequential Color Combinations: 3 Colors per Combination")
 
#display the "sequential" color combinations, with 9 colors per combination
#See Figure 3
display.brewer.all(n=9,type="seq",exact.n=TRUE)
title("Sequential Color Combinations: 9 Colors per Combination")

 
# convert R colors into RGB triplets;
col2rgb( brewer.pal("Accent", n=5) )