ggplot2:基于数据集中变量的 facet_wrap 条带颜色 [英] ggplot2: facet_wrap strip color based on variable in data set

问题描述

有没有办法根据数据框提供的变量填充使用 facet_wrap 创建的刻面条带?

Is there a way to fill the strips of facets created with facet_wrap based on a variable supplied with the data frame?

示例数据:

MYdata <- data.frame(fruit = rep(c("apple", "orange", "plum", "banana", "pear", "grape")), farm = rep(c(0,1,3,6,9,12), each=6), weight = rnorm(36, 10000, 2500), size=rep(c("small", "large")))

示例图:

p1 = ggplot(data = MYdata, aes(x = farm, y = weight)) + geom_jitter(position = position_jitter(width = 0.3), aes(color = factor(farm)), size = 2.5, alpha = 1) + facet_wrap(~fruit)

我知道如何更改条带的背景颜色(例如更改为橙色):

I know how to change the background color of the strips (e.g. to orange):

p1 + 主题(strip.background = element_rect(fill="orange"))

有没有办法将MYdata中变量size的值传递给element_rect中的参数fill代码>?

Is there a way to pass on the values in the variable size in MYdata to the parameter fill in element_rect?

基本上，我希望小水果(苹果、李子、梨)的背景颜色为绿色，而大水果(橙色、香蕉、葡萄)的背景颜色为红色，而不是所有条带的 1 种颜色.

Basically, instead of 1 color for all strips I would like the strip background color of small fruits (apple, plum, pear) to be green and the background color of large fruits (orange, banana, grape) to be red.

推荐答案

通过一些工作，您可以将您的情节与具有正确 grobs 的虚拟 gtable 结合起来，

With a little bit of work, you can combine your plot with a dummy gtable that has the right grobs,

d <- data.frame(fruit = rep(c("apple", "orange", "plum", "banana", "pear", "grape")), 
                farm = rep(c(0,1,3,6,9,12), each=6), 
                weight = rnorm(36, 10000, 2500), 
                size=rep(c("small", "large")))

p1 = ggplot(data = d, aes(x = farm, y = weight)) + 
  geom_jitter(position = position_jitter(width = 0.3), 
              aes(color = factor(farm)), size = 2.5, alpha = 1) + 
  facet_wrap(~fruit)

dummy <- ggplot(data = d, aes(x = farm, y = weight))+ facet_wrap(~fruit) + 
  geom_rect(aes(fill=size), xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf) +
  theme_minimal()

library(gtable)

g1 <- ggplotGrob(p1)
g2 <- ggplotGrob(dummy)

gtable_select <- function (x, ...) 
{
  matches <- c(...)
  x$layout <- x$layout[matches, , drop = FALSE]
  x$grobs <- x$grobs[matches]
  x
}

panels <- grepl(pattern="panel", g2$layout$name)
strips <- grepl(pattern="strip_t", g2$layout$name)
g2$layout$t[panels] <- g2$layout$t[panels] - 1
g2$layout$b[panels] <- g2$layout$b[panels] - 1

new_strips <- gtable_select(g2, panels | strips)
grid.newpage()
grid.draw(new_strips)

gtable_stack <- function(g1, g2){
  g1$grobs <- c(g1$grobs, g2$grobs)
  g1$layout <- transform(g1$layout, z= z-max(z), name="g2")
  g1$layout <- rbind(g1$layout, g2$layout)
  g1
}
## ideally you'd remove the old strips, for now they're just covered
new_plot <- gtable_stack(g1, new_strips)
grid.newpage()
grid.draw(new_plot)

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