使用 ggplot2 躲避哑铃图

这个问题是基于这个先前的问题。 https://stackoverflow.com/q/58756264/4975218

考虑以下情节：

Domain = c("A", "B", "C", "D", "E", "F", "G", 
           "A", "B", "C", "D", "E", "F", "G", "A", "B", "C", "D", "E", "F", 
           "G", "A", "B", "C", "D", "E", "F", "G") 

Area = c("State", "State", 
         "State", "State", "State", "State", "State", "National", "National", 
         "National", "National", "National", "National", "National", "State", 
         "State", "State", "State", "State", "State", "State", "National", 
         "National", "National", "National", "National", "National", "National")

race = c("White", "White", "White", "White", "White", "White", 
         "White", "White", "White", "White", "White", "White", "White", 
         "White", "Black", "Black", "Black", "Black", "Black", "Black", 
         "Black", "Black", "Black", "Black", "Black", "Black", "Black", 
         "Black") 

pct_agreement = c(0.557610213756561, 0.735042750835419, 
                  0.567375898361206, 0.633762538433075, 0.64091557264328, 0.750356614589691, 
                  0.564539015293121, 0.651861846446991, 0.697574973106384, 0.653521358966827, 
                  0.713940441608429, 0.680985689163208, 0.751584351062775, 0.642535984516144, 
                  0.488484561443329, 0.581625580787659, 0.456939995288849, 0.580652594566345, 
                  0.630399644374847, 0.711643815040588, 0.347775995731354, 0.627996683120728, 
                  0.668737232685089, 0.610245823860168, 0.690373718738556, 0.705771028995514, 
                  0.738830924034119, 0.550933301448822)

df <- data.frame(Domain, Area, race, pct_agreement)

library(tidyverse)

ggplot(df) +
  geom_point(
    aes(
      x = Domain, y = pct_agreement, color = Area, shape = race,
      group = Area
    ), 
    position = position_dodge(width = 1)
  ) +
  coord_flip()

现在我们想通过连接同一域和面积的每一对点将其变成哑铃图。明显的代码如下：

df2 <- pivot_wider(df, names_from = race, values_from = pct_agreement)

ggplot(df) +
  geom_point(
    aes(
      x = Domain, y = pct_agreement, color = Area, shape = race,
      group = Area
    ), 
    position = position_dodge(width = 1)
  ) +
  geom_segment(
    data = df2,
    aes(
      x = Domain, xend = Domain, y = White, yend = Black,
      color = Area
    ),
    position = position_dodge(width = 1)
  ) +
  coord_flip()

^{Created on 2019-11-08 by the reprex package https://reprex.tidyverse.org (v0.3.0)}

然而，显然这不起作用，因为position_dodge()并没有躲避xend审美的。我认为这是 ggplot2 中的一个错误，可能应该修复。然而，与此同时，制作这个情节最简单的方法是什么？我可以想到各种方法来做到这一点，但它们看起来都很麻烦。我错过了什么吗？

我发现嵌套分组通常会导致特定图出现困难。在这些情况下我发现interaction()函数非常有用，因为它允许简洁的代码并避免数据重新格式化。我们可以为线段定义一个新的分组。

重要的是，以下解决方案适用于位置躲避，因为它使用geom_line()代替geom_segment()。这避免了xend审美其中position_dodge()无法处理。

ggplot(df) +
  geom_point(
    aes(
      x = Domain, y = pct_agreement, color = Area,
      shape = race, group = Area
    ), 
    position = position_dodge(width = 0.5)
  ) +
  geom_line(
    aes(
      x = Domain, y = pct_agreement, color = Area, 
      group = interaction(Area, Domain)
    ),
    position = position_dodge(width = 0.5)
  ) +
  coord_flip()