# NOT RUN {
## generate color palette
pal <- diverge_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)])
# }
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