R语言ggplot2分面标签过长截断，如何让标签覆盖图表显示？

下面提供几种不用调整图表尺寸和字号的最优方案，让长分面标签完整展示：

方法1：让标签自动换行+调整边距 #

通过设置strip.text.x的wrap=TRUE让长标签自动换行，同时调整上下边距，避免标签被边框挤压：

library(ggplot2)

df <- data.frame(a = c(seq(1:10)), b = seq(1:10), group = c(rep('group1',5), rep('really_really_really_long_lable_here',5)), 
                 sex = c(rep(c('M','F'),5)))

ggplot(df, aes(sex,b, group = sex)) +
  geom_boxplot() +
  facet_wrap(~group, strip.position = "bottom") +
  theme(
    strip.placement = "outside",
    strip.background = element_blank(),
    text = element_text(size = 16),
    # 开启自动换行，同时设置上下边距
    strip.text.x = element_text(margin = margin(t = 10, b = 10), hjust = 0.5, wrap = TRUE)
  ) +
  xlab(NULL)

方法2：用markdown手动控制换行（更灵活） #

借助ggtext包支持markdown格式，手动给长标签插入换行符，精准控制换行位置：

先安装并加载包：

install.packages("ggtext")
library(ggtext)

修改标签并绘图：

# 替换下划线为空格，给长标签插入换行
df$group <- gsub("_", " ", df$group)
df$group[df$group == "really really really long lable here"] <- "really really really<br>long lable here"

ggplot(df, aes(sex,b, group = sex)) +
  geom_boxplot() +
  facet_wrap(~group, strip.position = "bottom") +
  theme(
    strip.placement = "outside",
    strip.background = element_blank(),
    text = element_text(size = 16),
    # 使用markdown格式渲染标签
    strip.text.x = element_markdown(margin = margin(t = 10, b = 10), hjust = 0.5)
  ) +
  xlab(NULL)

方法3：增加绘图底部内边距 #

如果不想换行，直接给图表底部加空白空间，让长标签完整展示：

ggplot(df, aes(sex,b, group = sex)) +
  geom_boxplot() +
  facet_wrap(~group, strip.position = "bottom") +
  theme(
    strip.placement = "outside",
    strip.background = element_blank(),
    text = element_text(size = 16),
    # 增加底部内边距，给长标签留出空间
    plot.margin = margin(b = 30, unit = "pt")
  ) +
  xlab(NULL)

内容的提问来源于stack exchange，提问作者Tomer9w