如何在R中绘制对称的两组排名对比图

你之前使用GGally::ggparcoord无法实现两侧各自排序的对称斜坡图效果，是因为ggparcoord默认共用统一y轴刻度，不能分别对左右两列排名做独立排序，以下是可直接运行的实现代码：

1. 加载依赖包 #

library(tidyverse)
library(hrbrthemes)
library(viridis)

2. 构造示例数据集 #

data <- data.frame(
  Group = letters[1:10],
  Ranking1 = 1:10,
  Ranking2 = c(1,4,2,3,7,5,9,11,6,16),
  Pop = c(12345,127868,123477,9485,132588,38741,8372,53423,238419,31314)
)

3. 数据预处理 #

把宽表转为长表，同时计算左右两侧的独立y轴位置（确保排名1在最上方，两侧各自按对应排名排序）：

plot_data <- data %>%
  pivot_longer(cols = c(Ranking1, Ranking2), names_to = "Rank_type", values_to = "Rank_val") %>%
  mutate(
    x_pos = ifelse(Rank_type == "Ranking1", 1, 2),
    y_pos = ifelse(Rank_type == "Ranking1", -Ranking1, -Ranking2)
  )

4. 绘制对称排名对比图 #

ggplot(plot_data, aes(x = x_pos, y = y_pos, group = Group, color = Group)) +
  # 中间连线
  geom_line(alpha = 0.7, linewidth = 1) +
  # 散点，大小映射人口数值
  geom_point(aes(size = Pop), alpha = 0.8) +
  # 左侧标注：组名+Ranking1数值
  geom_text(data = filter(plot_data, Rank_type == "Ranking1"),
            aes(x = 0.9, label = paste0(Group, " (", Rank_val, ")")),
            hjust = 1, size = 3.5) +
  # 右侧标注：组名+Ranking2数值
  geom_text(data = filter(plot_data, Rank_type == "Ranking2"),
            aes(x = 2.1, label = paste0(Group, " (", Rank_val, ")")),
            hjust = 0, size = 3.5) +
  # 两侧表头
  annotate("text", x = 1, y = 0, label = "Ranking1", size = 5, fontface = "bold") +
  annotate("text", x = 2, y = 0, label = "Ranking2", size = 5, fontface = "bold") +
  # 颜色和主题设置
  scale_color_viridis(discrete = TRUE) +
  scale_size_continuous(range = c(2, 8)) +
  theme_ipsum() +
  theme_void() +
  theme(
    legend.position = "none",
    plot.title = element_text(hjust = 0.5, size = 16)
  ) +
  # 调整x轴范围留出标注空间
  xlim(0.5, 2.5) +
  labs(title = "Ranking")

上述代码生成的图表两侧会分别按Ranking1、Ranking2的排名从上到下排列，中间用连线连接同一组的两个排名位置，完全匹配你需要的对称样式。你可以根据需求调整文本大小、点的大小范围、颜色映射规则等参数。

内容的提问来源于stack exchange，提问作者pepi.guerra