R语言ggplot2绘制多折线图如何在数据点旁添加数据标签

你现有代码基于宽格式数据编写，无需调整原始数据结构，直接新增对应文本图层即可在数据点周边显示数值标签。 #

基础实现：固定位置标签 #

直接在原有绘图代码中，为两个变量分别添加geom_text()图层，通过偏移参数控制标签与数据点的距离，避免遮挡点、线元素，修改后完整代码如下：

ggplot(data, aes(year)) + 
  geom_line(aes(y = var1), color = "#E20335", size = 1.5) +
  geom_point(aes(y = var1), color = "#E20335", size = 3) +
  # 为var1系列添加数据标签
  geom_text(aes(y = var1, label = scales::comma(var1)), 
            color = "#E20335", size = 3, nudge_y = 150) +
  geom_line(aes(y = var2), color = "#292753", size = 1.5) +
  geom_point(aes(y = var2), color = "#292753", size = 3) +
  # 为var2系列添加数据标签
  geom_text(aes(y = var2, label = scales::comma(var2)), 
            color = "#292753", size = 3, nudge_y = 150) +
  scale_x_continuous(breaks = 2010:2020) +
  scale_y_comma() +
  labs(title = 'something',
       subtitle = 'something',
       x = 'This axis title intentionally left blank',
       y = 'This axis title intentionally left blank',
       caption = 'something')

核心参数说明：

• label = scales::comma(var1)：让标签数值和y轴保持一致的千分位逗号格式，和你原有scale_y_comma()的显示效果匹配
• nudge_y = 150：控制标签相对于数据点的垂直偏移量，正数向上偏移、负数向下偏移，可根据你实际的y轴数值范围调整大小，数值范围大就调大该值，范围小就调小
• 如需调整水平方向位置，可添加nudge_x参数设置水平偏移量

优化实现：自动避重叠标签 #

如果两条折线的数值比较接近，固定偏移的标签容易出现互相遮挡的问题，可以替换为ggrepel包提供的geom_text_repel()图层，自动计算标签位置避开图形元素，无需手动反复调整偏移量：

1. 首次使用先安装包，之后每次使用加载即可：

   install.packages("ggrepel")
   library(ggrepel)
   

2. 修改后的绘图代码：

   ggplot(data, aes(year)) + 
     geom_line(aes(y = var1), color = "#E20335", size = 1.5) +
     geom_point(aes(y = var1), color = "#E20335", size = 3) +
     geom_text_repel(aes(y = var1, label = scales::comma(var1)), 
               color = "#E20335", size = 3, min.segment.length = 0.2) +
     geom_line(aes(y = var2), color = "#292753", size = 1.5) +
     geom_point(aes(y = var2), color = "#292753", size = 3) +
     geom_text_repel(aes(y = var2, label = scales::comma(var2)), 
               color = "#292753", size = 3, min.segment.length = 0.2) +
     scale_x_continuous(breaks = 2010:2020) +
     scale_y_comma() +
     labs(title = 'something',
          subtitle = 'something',
          x = 'This axis title intentionally left blank',
          y = 'This axis title intentionally left blank',
          caption = 'something')
   

简化代码写法（可选） #

如果后续需要添加更多折线，可以先把宽格式数据转为长格式，不用为每个变量重复写图层，代码可维护性更高：

library(tidyr)
# 宽表转长表
data_long <- pivot_longer(data, cols = c(var1, var2), names_to = "group", values_to = "val")

ggplot(data_long, aes(x = year, y = val, color = group)) +
  geom_line(size = 1.5) +
  geom_point(size = 3) +
  geom_text(aes(label = scales::comma(val)), nudge_y = 150, size = 3, show.legend = FALSE) +
  # 统一配置系列颜色
  scale_color_manual(values = c("var1" = "#E20335", "var2" = "#292753")) +
  scale_x_continuous(breaks = 2010:2020) +
  scale_y_comma() +
  labs(title = 'something',
       subtitle = 'something',
       x = 'This axis title intentionally left blank',
       y = 'This axis title intentionally left blank',
       caption = 'something')

内容的提问来源于stack exchange，提问作者onlyjust17