如何在ggplot2中叠加两个人口金字塔图并显示对应图例

需求说明 #

需要在ggplot2中绘制叠加式人口金字塔：以普查（census）数据生成浅色半透明底图，再叠加调查（survey）数据的深色金字塔（darkred对应女性、steelblue对应男性），同时图例需正确显示Male (c/s)、Female (c/s)标签（c代表普查，s代表调查）。

实现步骤 #

• 基于普查数据绘制基础柱状图，设置半透明浅色填充
• 在基础图上叠加调查数据的柱状图层，使用指定深色填充
• 通过scale_fill_manual统一配置四类性别标签对应的颜色，确保图例正确映射
• 修正原代码中的语法错误，调整文本标签、坐标轴及主题样式

完整代码 #

library(tidyverse)
library(ggplot2)

# 数据准备
census <- data.frame(
  age = c("20-29", "30-39", "40-49", "50-59", "60-69", "70+"),
  PopPerc = c(12.45, 14.14, 16.56, 14.73, 13.77, 11.00, -11.18, -13.13, -16.67, -15.10, -14.60, -13.82),
  sex = c("Male (c)", "Male (c)", "Male (c)", "Male (c)", "Male (c)", "Male (c)", "Female (c)", "Female (c)", "Female (c)", "Female (c)", "Female (c)", "Female (c)"),
  signal = c(1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1)
)

survey <- data.frame(
  age = c("20-29", "30-39", "40-49", "50-59", "60-69", "70+"),
  PopPerc = c(12.18, 24.70, 27.54, 19.22, 11.77, 4.60, -11.94, -25.76, -29.59, -18.11, -10.84, -3.76),
  sex = c("Male (s)", "Male (s)", "Male (s)", "Male (s)", "Male (s)", "Male (s)", "Female (s)", "Female (s)", "Female (s)", "Female (s)", "Female (s)", "Female (s)"),
  signal = c(1, 1, 1, 1, 1, 1, -1, -1, -1, -1, -1, -1)
)

# 构建叠加金字塔图
pyramid_plot <- census %>%
  ggplot(aes(x = age, y = PopPerc)) +
  # 普查数据底层：半透明浅色
  geom_bar(aes(fill = sex), stat = 'identity', alpha = 0.5) +
  # 普查数据百分比标签
  geom_text(aes(y = PopPerc + signal * 0.3, label = abs(PopPerc))) +
  # 调查数据上层：深色，调整宽度避免完全遮挡底层
  geom_bar(data = survey, aes(fill = sex), stat = 'identity', width = 0.7) +
  # 翻转坐标轴形成金字塔形态
  coord_flip() +
  # 统一配置填充颜色，对应所有四类标签
  scale_fill_manual(
    name = '',
    values = c(
      "Female (c)" = alpha("lightpink", 0.5),
      "Male (c)" = alpha("lightblue1", 0.5),
      "Female (s)" = "darkred",
      "Male (s)" = "steelblue"
    )
  ) +
  # Y轴格式化为百分比显示
  scale_y_continuous(
    labels = function(x) paste(abs(x), '%')
  ) +
  # 图表标签设置
  labs(
    x = '',
    y = '参与者占比',
    title = '普查与调查人口金字塔叠加图'
  ) +
  # 主题样式调整
  theme_classic() +
  theme(
    axis.text.x = element_text(vjust = 0.5),
    panel.grid.major.y = element_line(color = 'lightgray', linetype = 'dashed'),
    legend.position = 'top',
    legend.justification = 'center'
  )

# 输出图形
pyramid_plot

代码说明 #

• 两次调用geom_bar实现图层叠加，普查数据作为底层，调查数据通过width参数调整宽度，避免完全遮挡底层
• scale_fill_manual明确指定四个sex类别对应的颜色，确保图例与图形颜色一一对应
• 保留原有的文本标签、坐标轴翻转逻辑，同时修正了原代码中的语法错误

内容的提问来源于stack exchange，提问作者Chris T.