USSouthPolygon.RdCounty polygons for Alabama, Georgia, and South Carolina plus an artifical variable used for coloring.
data("USSouthPolygon")A data frame with coordinates of the vertices of the county polygons
(x, y) and an artificial variable z constructed for
illustrating colored maps.
Polygon data taken from maps package of Becker, Wilks, Brownrigg, and Minka (2012). Version 2.2-6. https://CRAN.R-project.org/package=maps
## generate color palette
pal <- diverging_hcl(9)
n <- length(pal)
## draw shaded polygons
plot(0, 0, type = "n", xlab = "", ylab = "", xaxt = "n", yaxt = "n", bty = "n",
xlim = c(-88.5, -78.6), ylim = c(30.2, 35.2), asp = 1)
polygon(USSouthPolygon, col = pal[cut(na.omit(USSouthPolygon$z), breaks = 0:n/n)])