A choropleth is a map which
Choropleths are useful for visualizing data where geographic boundaries are a natural unit of aggregation. For example, here is a choropleth that shows 2012 US State Population Estimates:
library(choroplethr) ?df_pop_state data(df_pop_state) state_choropleth(df_pop_state, title="2012 US State Population Estimates", legend="Population")
choroplethr is an R package that facilitates the creation of choropleth maps in R. It does this in 3 ways.
The remaining vignettes explain these features in more detail.