控制ggplot2 geom_bar的填充顺序和组 [英] Control the fill order and groups for a ggplot2 geom_bar

问题描述

library(ggplot2)


 data <- 
  data.frame(
    group=factor(c("a","c","b","b","c","a")),
    x=c("A","B","C", "D","E","F"),
    y=c(3,2,10,11,4,5)) 

> data
  group x  y
1     a A  3
2     c B  2
3     b C 10
4     b D 11
5     c E  4
6     a F  5

#And plot this:
ggplot(data)+
  geom_bar(aes(x=x, y=y, fill=group, order=group),
           stat="identity",
           position="dodge")+
  coord_flip()

这给出了一个图，其中x是根据因子水平绘制的:

This gives a figure where x is plotted according to factor levels:

但是如何根据group变量的自定义顺序对x重新排序，并同时根据降序y排列在group内.例如，如果我要先绘制"c"(红色)，然后再绘制"a"(绿色)，然后再绘制"b"(蓝色)，则x轴(x变量)的绘制顺序为:E ，B，F，A，D，C.请注意，这可能与

But how can one reorder x according to a custom order of the group variable and at the same time arrange within group according to say descending y. For instance if I want to plot first "c" (red), then "a" (green) and then "b" (blue) groups, the plot order of the x-axis (x variable) would be: E, B, F, A, D, C. Note this may have resemblance to this SO question.

推荐答案

您首先需要在不使用factor的情况下格式化数据框.然后，您需要将x列定义为factor，但顺序取决于每个group的最小y.您需要在levels参数中指定所需的特定顺序.

You need first to format your dataframe without factor. Then you need to define the x column as factor but with order depending on y minimum per group. This specific ordering you want needs to be specified in levels argument.

我们在这里:

data <- 
  data.frame(
    group=c("a","c","b","b","c","a"),
    x=c("A","B","C", "D","E","F"),
    y=c(3,2,10,11,4,5)) 

data$x = with(data, factor(x, levels=x[order(ave(y, group, FUN=min),y)]))

ggplot(data, aes(x, y, fill=group)) + 
  geom_bar(stat='identity', position='dodge') + 
  coord_flip()

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