在ggplot2中实现嵌套分组的多行Y轴标签（替代图例）

需求说明 #

想把group和term两个变量做成Y轴的两行标签（分组在上，变量名在下），同时让分组标签的颜色和对应点的颜色一致，替代原有的图例。

现有代码生成的图表：

想要的目标效果：

现有代码：

data <- tibble::tribble(                       ~ term,   ~estimate, ~conf.low, ~conf.high,           ~group,           
"HH cultivated plots",                                         0.0163,  -0.0130,    0.0456, "Extensive Margin",
"# of farm assets (hoe, spade, axe), all HHs",                 0.356,    0.143,     0.569,  "Assets",          
"Number of plots",                                            -0.0539,  -0.158,     0.0498, "Intensive Margin",
"Farm size",                                                   0.208,   -0.0394,    0.456,  "Intensive Margin",
"# of HH members that cultivated plots, all HHs",              0.0541,  -0.0647,    0.173,  "Intensive Margin",
"Avg # of days HH members spent cultivating plots, all HHs",  -0.192,   -0.738,     0.354,  "Intensive Margin",
"Annual agricultural revenue",                                 0.329,    0.170,     0.487,  "Revenue")

ag_coef_plot <- data %>%
  ggplot(
    aes(x =  estimate, 
        y = term,
        color = group
  )) +
  geom_pointrange( # Confidence interval
    aes(
      xmin = conf.low, 
      xmax = conf.high
    ), 
    show.legend = FALSE,
  ) +
  scale_x_continuous(name = "") +
  geom_vline(xintercept = 0) +
  scale_y_discrete(name = "", 
                   limits = rev, 
                   expand = c(.05, 0)) + 
  theme_minimal() + 
  theme(
    plot.title          = element_text(size = 15, hjust = 0.5, face = "bold"),
    plot.title.position = "plot",
    plot.background     = element_rect(color = "black"), # 用于确保背景色不为黑色
    axis.text.y         =  element_text(size = 15),
    axis.text.x         =  element_text(size = 15),
    legend.position     = "left",
    legend.title        = element_blank(),
    legend.text         = element_blank()
  ) +
  scale_color_brewer(palette = "Set2") 

ag_coef_plot

解决办法 #

要实现目标效果，试试下面的代码：

library(tidyverse)
library(ggtext)

# 先给数据排序，保证同组的变量在Y轴上连续排列
data_sorted <- data %>%
  arrange(group, desc(term)) %>%
  mutate(term = factor(term, levels = term))

# 提取Set2调色板的颜色，和分组一一对应
group_colors <- scales::brewer_pal(palette = "Set2")(length(unique(data_sorted$group)))
names(group_colors) <- unique(data_sorted$group)

# 生成带颜色的Y轴标签：分组名（带对应颜色）换行+变量名
data_sorted <- data_sorted %>%
  mutate(y_label = glue::glue("<span style='color:{group_colors[group]}'>{group}</span><br>{term}"))

# 绘制图表
ag_coef_plot <- data_sorted %>%
  ggplot(aes(x = estimate, y = y_label, color = group)) +
  geom_pointrange(aes(xmin = conf.low, xmax = conf.high), show.legend = FALSE) +
  scale_x_continuous(name = "") +
  geom_vline(xintercept = 0) +
  scale_y_discrete(name = "", limits = rev, expand = c(.05, 0)) +
  scale_color_brewer(palette = "Set2") +
  theme_minimal() +
  theme(
    plot.title = element_text(size = 15, hjust = 0.5, face = "bold"),
    plot.title.position = "plot",
    plot.background = element_rect(color = "black"),
    axis.text.y = element_markdown(size = 15, hjust = 1), # 用element_markdown渲染带样式的文本
    axis.text.x = element_text(size = 15),
    legend.position = "none" # 彻底去掉图例
  )

ag_coef_plot

关键点说明 #

• 数据排序：确保同一分组的变量在Y轴上挨在一起，排版更整齐；
• 颜色绑定：提前提取Set2调色板的颜色，让分组标签和对应点的颜色完全匹配；
• 富文本标签：用glue生成带HTML颜色样式的标签，再通过ggtext的element_markdown渲染，实现多行带颜色的Y轴标签；
• 对齐调整：hjust = 1让Y轴文本右对齐，保证两行标签排版整齐。

内容的提问来源于stack exchange，提问作者Paula