如何使所有低于阈值的值具有连续刻度的单色? [英] How to make all values below a threshold have single color with scale continuous?

问题描述

我想将变量映射到连续的色标，但是如果该值低于某个阈值，则它应该具有特定的颜色.在此示例中，我想使用 mpg<20 用灰色填充，上面的所有内容都使用连续的色标:

 库(ggplot2)达特<-头(mtcars)dat $ model<-头(colnames(mtcars))dat $ is_low<-ifelse(dat $ mpg< 20，TRUE，FALSE)ggplot(dat，aes(x =模型，y = mpg，填充= mpg))+geom_col() 

那有可能吗?我所看到的最接近的是此

I would like to map a variable to a continuous color scale, but if the value is a below a certain threshold, it should have a specific color. In this example, I would like to make all car models with an mpg < 20 filled with gray, and everything above with the continuous color scale:

library(ggplot2)
dat <- head(mtcars)
dat$model <- head(colnames(mtcars))
dat$is_low <- ifelse(dat$mpg < 20, TRUE, FALSE)

ggplot(dat, aes(x = model, y = mpg, fill = mpg)) +
    geom_col()

Is that even possible? The closest I have seen is this solution but it maps a second variably to scale_color and not to scale_fill_continuous

解决方案

Not the most elegant, but you could add a layer that's filtered to just the ones you want gray:

ggplot(dat, aes(x = model, y = mpg, fill = mpg)) +
  geom_col() +
  geom_col(data = dat[dat$is_low,], fill = "gray70")

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