R中ggplot2中标签内的下标

发布于11月30日

这是这个问题的延续:Labeling facet strips in ggplot2

通过使用以下代码，我可以获得每个子图顶部的Year=2009，Year=2010:

set.seed(1)
df=data.frame(year=rep(2009:2013,each=4),
              quarter=rep(c("Q1","Q2","Q3","Q4"),5),
              sales=40:59+rnorm(20,sd=5))
library(ggplot2)
ggplot(df) +
  geom_line(aes(x=quarter,y=sales,group=year))+
  facet_wrap(
    .~year,
    labeller = as_labeller(\(x) paste0("Year=", x)),
    strip.position = "top",
    scales = "free") +
  theme(#panel.spacing = unit(0, "lines"),
    strip.placement = "outside",
    axis.title.x=element_blank(),
    legend.position="none")

如果我需要一个下标，例如，我需要显示年份a_b=2009，而不是年份=2009，我应该如何修改上述代码

我试着给你

... +
  facet_wrap(
    .~year,
    labeller = as_labeller(\(x) paste0("Year", bquote(a[b]) ,"=", x)),
    strip.position = "top",
    scales = "free"
  ) +
  ...

但它失败了.

推荐答案

您可以try 使用Unicode值作为下标，例如

library(tidyverse)
set.seed(1)
df=data.frame(year=rep(2009:2013,each=4),
              quarter=rep(c("Q1","Q2","Q3","Q4"),5),
              sales=40:59+rnorm(20,sd=5))

ggplot(df) +
  geom_line(aes(x=quarter,y=sales,group=year))+
  facet_wrap(
    .~year,
    labeller = as_labeller(\(x) paste0("Year a\u2090 = ", x)),
    strip.position = "top",
    scales = "free") +
  theme(#panel.spacing = unit(0, "lines"),
    strip.placement = "outside",
    axis.title.x=element_blank(),
    legend.position="none")