ggplot2：facet_wrap基于数据集中变量的条带颜色

Question

有没有办法根据数据框提供的变量填充使用facet_wrap创建的facet条？

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（例如橙色）：

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

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

基本上，对于所有条带而不是1种颜色，我希望小水果（苹果，李子，梨）的条带背景颜色为绿色，大果实（橙色，香蕉，葡萄）的背景颜色为红色。

Answer 1

通过一些工作，您可以将您的情节与具有正确凹凸的虚拟gtable结合起来，

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)

Answer 2

您可以找到有关此问题here的更新答案。

g <- ggplot_gtable(ggplot_build(p))
stripr <- which(grepl('strip-r', g$layout$name))
fills <- c("red","green","blue","yellow")
k <- 1
for (i in stripr) {
  j <- which(grepl('rect', g$grobs[[i]]$grobs[[1]]$childrenOrder))
  g$grobs[[i]]$grobs[[1]]$children[[j]]$gp$fill <- fills[k]
  k <- k+1
}
grid::grid.draw(g)

Answer 3

我很想知道如何做到这一点，这是一个好主意。一个想法是使用不同的颜色独立生成每个图表，然后使用多色图或视口等并排显示 - 这将需要更多的工作。

如果你想提取这个方法所需要的图例 - 这里有一些来自哈德利的代码，我发现了一段时间

g_legend<-function(a.gplot){
  tmp <- ggplot_gtable(ggplot_build(a.gplot))
  leg <- which(sapply(tmp$grobs, function(x) x$name) == "guide-box")
  legend <- tmp$grobs[[leg]]
  return(legend)}

看看如何从图表p中提取它，然后我把它从图中取出     传奇＆lt; - g_legend（p）     lwidth＆lt; - sum（图例$ width）＃如果要基于此定义视口     p＆lt; - p + theme（legend.position =“none”）

然后你最终画出它

grid.newpage()
vp <- viewport(width = 1, height = 1)
#print(p, vp = vp)

submain <- viewport(width = 0.9, height = 0.9, x = 0.5, y = 1,just=c("center","top"))
print(p, vp = submain)
sublegend <- viewport(width = 0.5, height = 0.2, x = 0.5, y = 0.0,just=c("center","bottom"))
print(arrangeGrob(legend), vp = sublegend)

祝你好运

Answer 4

这不是直接为各个方面着色的方法，而是基于两个变量（size ~ fruit，而不是一个（~ fruit）的方案，这是另一个（非常快速和简单的）解决方案：

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(size ~ fruit)