coord_flip 后分组条形图中数据的翻转顺序

Question

我遇到了一个烦人的问题，我无法找到具体的解决方案。我正在尝试创建一个水平分组条形图；我想要的只是获取标准的垂直条形图并将其向右旋转 90 度。当我使用 coord_flip 时，它会将绘图向右旋转，但会翻转（反转）每组 内 数据的顺序。这是一个例子：

library("ggplot2")

df <- data.frame(Group = c("A","A","A","B","B","B","C","C","C"),
                 Sub = c("1","2","3","1","2","3","1","2","3"),
                 Score = c(1,2,3,1,2,3,1,2,3))

df$Group <- factor(df$Group,
                       levels = c("A","B","C"),
                       labels = c("A","B","C"),
                       ordered = TRUE)

df$Sub <- factor(df$Sub,
                  levels = c("1","2","3"),
                  labels = c("1","2","3"),
                  ordered = TRUE)

ggplot(data = df, aes(x = Group, y = Score, fill = Sub)) +
  geom_bar(stat="identity", position=position_dodge()) +
  coord_flip() +
  scale_x_discrete(limits = rev(levels(df$Group)))

我可以使用以下方法按正确的顺序排列组：

scale_x_discrete(limits = rev(levels(df$Group)))

但是，我无法让每个组内 的顺序正确。图例和数据是相反的，在这种情况下，我想改变绘制数据的顺序，而不是图例的顺序。

我发现您可以通过将条形图的位置闪避设置为 -.9 来解决此问题，如下所示：

geom_bar(stat="identity", position=position_dodge(-.9))

鉴于我的分组变量是字符串，我不确定here 提出的解决方案是否可行。

任何帮助将不胜感激！

Answer 1

如果您熟悉 forcats 包，fct_rev() 非常方便在绘图时反转因子水平，并且可以在翻转坐标之前轻松反转图例顺序/颜色映射以匹配原始版本：

library(forcats)
library(ggplot2)

# unflipped version
p1 <- ggplot(data = df, 
       aes(x = Group, y = Score, fill = Sub)) +
  geom_col(position="dodge") #geom_col is equivalent to geom_bar(stat = "identity")

# flipped version
p2 <- ggplot(data = df, 
       aes(x = fct_rev(Group), y = Score, fill = fct_rev(Sub))) +
  geom_col(position="dodge") +
  coord_flip() +
  scale_fill_viridis_d(breaks = rev, direction = -1)

gridExtra::grid.arrange(p1, p2, nrow = 1)