r - 如何突出显示州内的特定县？

Question

如何突出显示州内的特定县？

states <- map_data("state")
south_coast <- subset(counties, region %in% c("texas", "oklahoma", "kansas"))
ggplot(data = south_coast) + 
  labs(title="Southern Plains of US",subtitle = "Plague positive counties") +
  geom_polygon(aes(x = long, y = lat, fill=region, group = group), color = "black") + 
  coord_fixed(1.2) + 
  guides(fill=FALSE)+theme_bw()

标签： rggplot2