R usmap - 如何显示两个不同的 colors：一个用于正值梯度，另一个显示负值

Question

Below is my current code for the graph. How can I make two different colors by having 0 as middle point eg. red in positive number and blue in negative number.

 plot_usmap(data = df2, values = "diffProviderPerFFS", color = "white") +
      scale_fill_continuous(name = "Provider Per 1000 FFS(2017-2016)", low="light green",high="dark green", label = scales::comma) +
      theme(legend.position = "right")

Answer 1

Obviously I din't have your data, so I've made some up. You should be able to get what you want with scale_fill_gradientn :

library(usmap)

df2 <- usmap::statepop
df2$diffProviderPerFFS <- runif(nrow(df2), -0.2, 0.5)

plot_usmap(data = df2, values  = "diffProviderPerFFS", color = "white") +
  scale_fill_gradientn(name    = "Provider Per 1000 FFS(2017-2016)", 
                       colours = c("red", "white", "forestgreen"),
                       breaks  = c(-0.2, 0, 0.2),
                       label   = scales::comma) +
  theme(legend.position = "right")