facet_wrap 的百分比直方图

Question

我正在尝试将百分比直方图与 facet_wrap 相结合，但百分比不是基于组计算的，而是基于所有数据计算的。我希望每个直方图显示一组中的分布，而不是相对于所有人口的分布。我知道可以做几个图并将它们与 multiplot.

结合起来

library(ggplot2)
library(scales)
library(dplyr)

set.seed(1)
df <- data.frame(age = runif(900, min = 10, max = 100),
                 group = rep(c("a", "b", "c", "d", "e", "f", "g", "h", "i"), 100))

tmp <- df %>%
  mutate(group = "ALL")

df <- rbind(df, tmp)

ggplot(df, aes(age)) + 
  geom_histogram(aes(y = (..count..)/sum(..count..)), binwidth = 5) + 
  scale_y_continuous(labels = percent ) + 
  facet_wrap(~ group, ncol = 5)

输出：

Answer 1

尝试使用 y = stat(density)（或 ggplot2 版本 3.0.0 之前的 y = ..density..）而不是 y = (..count..)/sum(..count..)

ggplot(df, aes(age, group = group)) + 
  geom_histogram(aes(y = stat(density) * 5), binwidth = 5) + 
  scale_y_continuous(labels = percent ) +
  facet_wrap(~ group, ncol = 5)

来自“计算变量”下的 ?geom_histogram

density : density of points in bin, scaled to integrate to 1

我们乘以 5（bin 宽度），因为 y 轴是密度（面积积分为 1），而不是百分比（高度总和为 1），参见 Hadley's comment（感谢@MariuszSiatka).

Answer 2

虽然似乎 facet_wrap 没有运行每个子集中的特殊 geom_histogram 百分比计算，但考虑单独构建一个地块列表，然后将它们网格排列在一起。

具体来说，调用 by 到运行你的 ggplots 在 group 的子集中，然后调用 gridExtra::grid.arrange() （实际的包方法）有点模仿 facet_wrap:

library(ggplot2)
library(scales)
library(gridExtra)

...

grp_plots <- by(df, df$group, function(sub){
  ggplot(sub, aes(age)) + 
    geom_histogram(aes(y = (..count..)/sum(..count..)), binwidth = 5) + 
    scale_y_continuous(labels = percent ) + ggtitle(sub$group[[1]]) +
    theme(plot.title = element_text(hjust = 0.5))
})

grid.arrange(grobs = grp_plots, ncol=5)

但是为了避免重复的 y 轴和 x 轴，考虑在 by 调用中有条件地设置 theme，假设您提前了解您的组并且他们在数字。

grp_plots <- by(df, df$group, function(sub){

  # BASE GRAPH
  p <- ggplot(sub, aes(age)) + 
    geom_histogram(aes(y = (..count..)/sum(..count..)), binwidth = 5) + 
    scale_y_continuous(labels = percent ) + ggtitle(sub$group[[1]])

  # CONDITIONAL theme() CALLS
  if (sub$group[[1]] %in% c("a")) {
    p <- p + theme(plot.title = element_text(hjust = 0.5), axis.title.x = element_blank(), 
                  axis.text.x = element_blank(), axis.ticks.x = element_blank())
  }
  else if (sub$group[[1]] %in% c("f")) {
    p <- p + theme(plot.title = element_text(hjust = 0.5))
  }
  else if (sub$group[[1]] %in% c("b", "c", "d", "e")) {
    p <- p + theme(plot.title = element_text(hjust = 0.5), axis.title.y = element_blank(), 
                   axis.text.y = element_blank(), axis.ticks.y = element_blank(),
                   axis.title.x = element_blank(), axis.text.x = element_blank(), 
                   axis.ticks.x = element_blank())
  }
  else {
    p <- p + theme(plot.title = element_text(hjust = 0.5), axis.title.y = element_blank(), 
                   axis.text.y = element_blank(), axis.ticks.y = element_blank())
  }
  return(p)
})

grid.arrange(grobs=grp_plots, ncol=5)

facet_wrap 的百分比直方图

Percentage histogram with facet_wrap

r

histogram

ggplot2

facet-wrap