在挣扎了一段时间后，我发现我们可以使用fct_relevel()和fct_recode()从forcats结合来改变facet的顺序以及修复facet标签。我不确定它是否被设计支持，但它确实有效!看看下面的图表:

library(tidyverse)

before <- mpg %>%
  ggplot(aes(displ, hwy)) + 
  geom_point() +
  facet_wrap(~class)
before

after <- mpg %>%
  ggplot(aes(displ, hwy)) + 
  geom_point() + 
  facet_wrap(
    vars(
      # Change factor level name
      fct_recode(class, "motorbike" = "2seater") %>% 
        # Change factor level order
        fct_relevel("compact")
    )
  )
after

由reprex包于2020-02-16创建(v0.3.0)

添加另一个类似于@domi的解决方案，解析数学符号、上标、下标、圆括号/方括号等。

library(tidyverse)
theme_set(theme_bw(base_size = 18))

### create separate name vectors
# run `demo(plotmath)` for more examples of mathematical annotation in R
am_names <- c(
  `0` = "delta^{15}*N-NO[3]^-{}",
  `1` = "sqrt(x,y)"
)

# use `scriptstyle` to reduce the size of the parentheses &
# `bgroup` to make adding `)` possible 
cyl_names <- c(
  `4` = 'scriptstyle(bgroup("", a, ")"))~T~-~5*"%"',
  `6` = 'scriptstyle(bgroup("", b, ")"))~T~+~10~degree*C',
  `8` = 'scriptstyle(bgroup("", c, ")"))~T~+~30*"%"'
)

ggplot(mtcars, aes(wt, mpg)) + 
  geom_jitter() +
  facet_grid(am ~ cyl,
             labeller = labeller(am  = as_labeller(am_names,  label_parsed),
                                 cyl = as_labeller(cyl_names, label_parsed))
             ) +
  geom_text(x = 4, y = 25, size = 4, nudge_y = 1,
            parse = TRUE, check_overlap = TRUE,
            label = as.character(expression(paste("Log"["10"], bgroup("(", frac("x", "y"), ")")))))

### OR create new variables then assign labels directly
# reverse facet orders just for fun
mtcars <- mtcars %>% 
  mutate(am2  = factor(am,  labels = am_names),
         cyl2 = factor(cyl, labels = rev(cyl_names), levels = rev(attr(cyl_names, "names")))
  )

ggplot(mtcars, aes(wt, mpg)) + 
  geom_jitter() +
  facet_grid(am2 ~ cyl2,
             labeller = label_parsed) +
  annotate("text", x = 4, y = 30, size = 5,
           parse = TRUE, 
           label = as.character(expression(paste("speed [", m * s^{-1}, "]"))))

由reprex包于2019-03-30创建(v0.2.1.9000)

更改底层因子级别的名称，如下所示:

# Using the Iris data
> i <- iris
> levels(i$Species)
[1] "setosa"     "versicolor" "virginica" 
> levels(i$Species) <- c("S", "Ve", "Vi")
> ggplot(i, aes(Petal.Length)) + stat_bin() + facet_grid(Species ~ .)

下面是我如何使用2.2.1版本的ggplot2使用facet_grid(yfacet~xfacet):

facet_grid(
    yfacet~xfacet,
    labeller = labeller(
        yfacet = c(`0` = "an y label", `1` = "another y label"),
        xfacet = c(`10` = "an x label", `20` = "another x label")
    )
)

请注意，这里不包含对as_labeller()的调用——这一点我曾纠结过一段时间。

这种方法的灵感来自帮助页面上的最后一个示例强制到标签器函数。

从米沙巴利亚辛来的一条航线 ：

facet_grid(。~vs, labeller = purrr::partial(label_both, sep = " #"))

看看它的实际应用

library(reprex)
library(tidyverse)

mtcars %>% 
  ggplot(aes(x="", y=gear,fill=factor(gear), group=am)) +
  geom_bar(stat="identity", width=1) +
  coord_polar("y", start=0) +
  facet_grid(.~vs, labeller = purrr::partial(label_both, sep = " #"))

由reprex包于2021-07-09创建(v2.0.0)

我觉得我应该加上我的答案，因为我花了很长时间才做到这一点:

这个答案是为你准备的:

您不想编辑原始数据 如果你需要表达式(bquote)在标签和 如果您想要单独的标签名称-向量的灵活性

我基本上把标签放在一个命名向量中，这样标签就不会混淆或切换。标签器表达式可能更简单，但这至少是可行的(非常欢迎改进)。注意'(后引号)以保护facet-factor。

n <- 10
x <- seq(0, 300, length.out = n)

# I have my data in a "long" format
my_data <- data.frame(
  Type = as.factor(c(rep('dl/l', n), rep('alpha', n))),
  T = c(x, x),
  Value = c(x*0.1, sqrt(x))
)

# the label names as a named vector
type_names <- c(
  `nonsense` = "this is just here because it looks good",
  `dl/l` = Linear~Expansion~~Delta*L/L[Ref]~"="~"[%]", # bquote expression
  `alpha` = Linear~Expansion~Coefficient~~alpha~"="~"[1/K]"
  )


ggplot() + 
  geom_point(data = my_data, mapping = aes(T, Value)) + 
  facet_wrap(. ~ Type, scales="free_y", 
             labeller = label_bquote(.(as.expression(
               eval(parse(text = paste0('type_names', '$`', Type, '`')))
               )))) +
  labs(x="Temperature [K]", y="", colour = "") +
  theme(legend.position = 'none')