绘制数据均值、中位数竖线时遇unexpected symbol报错求助

你的代码存在三处语法错误，直接导致了unexpected symbol报错：

• geom_vline(data = gap (aes(...))处误用括号代替逗号，应改为data = gap, aes(...)，用逗号分隔data参数与aes映射
• aes(xintercept = mean(infant_mortality))col = "#92d6d5"处，aes()与col参数之间缺少逗号，需添加逗号分隔
• 最后一行geom_vline语句未闭合括号，末尾缺失一个)

修正后的完整代码：

gap %>%
  ggplot(aes(x = infant_mortality, col = region)) +
  geom_histogram(binwidth = 10) + 
  geom_vline(data = gap, aes(xintercept = mean(infant_mortality)), col = "#92d6d5") +
  geom_vline(data = gap, aes(xintercept = median(infant_mortality)), col = "#a4c27f")

额外补充：若想按region分组绘制各组的均值/中位数竖线，可先对数据分组汇总，再传入geom_vline，示例如下：

summary_gap <- gap %>% 
  group_by(region) %>% 
  summarize(mean_im = mean(infant_mortality), median_im = median(infant_mortality))

gap %>%
  ggplot(aes(x = infant_mortality, col = region)) +
  geom_histogram(binwidth = 10) + 
  geom_vline(data = summary_gap, aes(xintercept = mean_im, col = region)) +
  geom_vline(data = summary_gap, aes(xintercept = median_im, col = region), linetype = "dashed")

内容的提问来源于stack exchange，提问作者Cristina Raventos