如何用coord_cartesian(xlim=..)创建X轴断裂？为何代码截断异常值？

核心问题出在你的TotalP列是字符类型，不是数值型——ggplot处理离散x轴时，coord_cartesian()的xlim参数没法扩展轴范围，只会截断显示，导致400这个异常值被隐藏。下面给两种可行的解决方案：

方案一：修正数据类型 + 用coord_cartesian保留完整范围 #

先把TotalP转为数值型，再调整x轴刻度，既能保留常规区间的清晰刻度，又能包含异常值：

library(tidyverse)

TotalPhosphorus <- tibble(
  Depth = c('1' ,'2', '3' , '1', '2', '3'),
  Date = c('1/18/2021', '1/18/2021', '1/18/2021', '7/11/2021', '7/11/2021', '7/11/2021'),
  DOY = c('18', '18', '18', '70', '70', '70'),
  Season= c("winter", "winter", "winter", "summer", "summer", "summer"),
  TotalP = as.numeric(c('20', '30', '400', '25', '30', '25')) # 转换为数值型
)

TotalPhosphorus %>%
  ggplot(aes(x = TotalP, y = Depth, colour = Season, group = Season)) +
  geom_point() +
  geom_path() +
  scale_x_continuous(breaks = c(0, 50, 100, 400), # 手动添加异常值刻度
                     limits = c(0, NA)) + # 固定下限0，上限自动适配数据
  coord_cartesian(xlim = c(0, 400)) + # 确保显示范围覆盖异常值
  theme_bw()

方案二：用ggbreak做断裂轴（适合异常值差距极大的场景） #

如果异常值和常规数据差距过大，用断裂轴可以避免x轴被拉得过长，同时保留所有数据点：

library(tidyverse)
library(ggbreak)

TotalPhosphorus <- tibble(
  Depth = c('1' ,'2', '3' , '1', '2', '3'),
  Date = c('1/18/2021', '1/18/2021', '1/18/2021', '7/11/2021', '7/11/2021', '7/11/2021'),
  DOY = c('18', '18', '18', '70', '70', '70'),
  Season= c("winter", "winter", "winter", "summer", "summer", "summer"),
  TotalP = as.numeric(c('20', '30', '400', '25', '30', '25'))
)

TotalPhosphorus %>%
  ggplot(aes(x = TotalP, y = Depth, colour = Season, group = Season)) +
  geom_point() +
  geom_path() +
  scale_x_continuous(breaks = c(0, 50, 100, 400)) +
  scale_x_break(c(120, 380), # 设置断裂区间，跳过中间无数据的范围
                scales = 1) +
  theme_bw()

内容的提问来源于stack exchange，提问作者Daniela