r - 使用ggplot在多个条形图中添加组信息

Question

假设我有下面的多个条形图和 ggplot

raw <- read.csv("http://pastebin.com/raw.php?i=L8cEKcxS",sep=",")
raw[,2]<-factor(raw[,2],levels=c("Very Bad","Bad","Good","Very Good"),ordered=FALSE)
raw[,3]<-factor(raw[,3],levels=c("Very Bad","Bad","Good","Very Good"),ordered=FALSE)
raw[,4]<-factor(raw[,4],levels=c("Very Bad","Bad","Good","Very Good"),ordered=FALSE)

raw=raw[,c(2,3,4)] 

freq=table(col(raw), as.matrix(raw)) # get the counts of each factor level
Names=c("Food","Music","People")     
data=data.frame(cbind(freq),Names)   
data=data[,c(5,3,1,2,4)]             


data.m <- melt(data, id.vars='Names')


ggplot(data.m, aes(Names, value)) +   
  geom_bar(aes(fill = variable), position = "dodge", stat="identity")

这很好。不过，我想沿 x 轴 添加一些组信息。假设 2 个组被定义为 Group1:食物和音乐 和 Group2:人。有了这个，我正在尝试构建一个 ggplot 如下所示

我还想减少 Food & Music 之间的空间并增加 Music & People 之间的空间 - 只是为了演示 Food & Music组成 1 组和 People 另一组。

有什么方法可以使用 ggplot 框架实现这一点？

Answer 1

有几个选项，例如将组信息作为注释添加到您的绘图中。但恕我直言，一个好的起点和最简单的方法是使用分面:

使用一些假的示例数据:

library(ggplot2)

variable <- c("Very Bad","Bad","Good","Very Good")

data.m <- data.frame(
  Names = rep(c("Food","Music","People"), each = 4),
  value = 1:12,
  variable = factor(variable, levels = variable)
)
data.m$group <- ifelse(data.m$Names %in% c("Food", "Music"), "Group 1", "Group 2")

ggplot(data.m, aes(Names, value)) +   
  geom_bar(aes(fill = variable), position = "dodge", stat="identity") +
  facet_grid(.~group, space = "free", scales = "free_x", switch = "x") +
  theme(strip.placement = "outside",
        strip.background.x = element_rect(fill = NA),
        strip.text.x = element_text(color = "red"))