r - 如何使用 ggplot2 和 geom_tile 创建自定义色标？

Question

我想修改颜色渐变以匹配一组预定义的阈值/切点和颜色。我怎样才能做到这一点？

截止值:-0.103200、0.007022、0.094090、0.548600
颜色:“#EDF8E9”、“#BAE4B3”、“#74C476”、“#238B45”

    #Create sample data

        pp <- function (n,r=4) {
              x <- seq(-r*pi, r*pi, len=n)
              df <- expand.grid(x=x, y=x)
              df$r <- sqrt(df$x^2 + df$y^2)
              df$z <- cos(df$r^2)*exp(-df$r/6)
              df
            }

            pp(20)->data

#create the plot

library(ggplo2)
            p <- ggplot(pp(20), aes(x=x,y=y))
            p + geom_tile(aes(fill=z))

#Generate custom colour ramp

library(RColorBrewer)

cols <- brewer.pal(4, "Greens")

Answer 1

你可以试试 scale_fill_brewer .首先，将您的 z 值装箱:

df <- pp(20)
df$z_bin <- cut(df$z, breaks = c(-Inf, -0.103200, 0.007022, 0.094090, 0.548600))

阴谋:

ggplot(data = df, aes(x = x, y = y, fill = z_bin)) +
  geom_tile() +
  scale_fill_brewer(palette = "Greens")