Show a palette using a map of U.S. counties

What to look for:

Usage

pal.map(pal = brewer.paired, n = 12, main = "")

Arguments

pal

A palette function or a vector of colors.

n

Number of colors to return.

main

Main title

Value

None

Details

1. Are regions distinct?

2. Are outliers within each region distinct?

Display a palette on a choropleth map similar to ColorBrewer.

Broad bands of color are easy to distinguish. Does the palette allow visibility of outlier counties in the larger regions? Does the palette allow identification of colors when the pattern is more complex (as in the lower left corner of the map)?

Notes. The map shown by the ColorBrewer website is an SVG here https://github.com/axismaps/colorbrewer/tree/master/map/map.svg which contains the class identifier for each polygon, for 3 to 12 classes. Unfortunately, the polygons have no other identification (e.g. FIPS, county name). We used the identify.map function in R to manually define the classes similar to the 12-class map of ColorBrewer. This proved to be too tedious to do more than once, so our maps of 1-11 classes were created by combining classes from the 12-class map. The ColorBrewer website sometimes used this strategy to combine classes, but not always. The 'outlier' counties and 'random region' in this version are very similar to the 12-region map of ColorBrewer, but there are a few differences, mostly intentional. Also, the map projection used here is different from ColorBrewer.

References

http://www.personal.psu.edu/cab38/Pub_scans/Brewer_pubs.html Map based on www.ColorBrewer.org, by Cynthia A. Brewer, Penn State.

Author

Kevin Wright

Examples

pal.map(brewer.paired, main="brewer.paired")

pal.map(parula)


if (FALSE) { # \dontrun{
for(i in 3:12){
  pal.map(n=i, main=i)
}
} # }