if (require("maps")) {
ca <- map("county", "ca", plot = FALSE, fill = TRUE)
head(fortify(ca))
qplot(long, lat, data = ca, geom = "polygon", group = group)
tx <- map("county", "texas", plot = FALSE, fill = TRUE)
head(fortify(tx))
qplot(long, lat, data = tx, geom = "polygon", group = group,
colour = I("white"))
}
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