R ggplot2 在同一类别标签中使用斜体和非斜体 [英] R ggplot2 using italics and non-italics in the same category label

问题描述

对于我的 ggplot 图，我想在条形图上标记类别，第一个单词是斜体，而后面的单词是非斜体.我希望类别标签如下所示:

For my ggplot figure, I want to label categories on a barplot with the first word being italicized, while the following words are non-italicized. I want the category labels to look like follows:

葡萄球菌 (OTU 1)

链球菌 (OTU 300)

我找到了使用 expression() 的示例，我可以在其中将一些类别标签斜体化，但我希望能够为许多不同的类别执行此操作.

I've found examples using expression() where I can italicize a few category labels, but I would like to be able to do this for many different categories.

绘制图的代码如下(但我的数据有更多的条要绘制).

The code to make a plot is as follows (but my data has many more bars to plot).

library(ggplot2)

data <- data.frame(
  bactname = c("Staphylococcaceae", "Moraxella", "Streptococcus", "Acinetobacter"),
  OTUname = c("OTU_1", "OTU_2", "OTU_3", "OTU_4"),
  value = c(-0.5, 0.5, 2, 3)
)

data$name <- paste0(
  data$bactname, " (", data$OTUname, ")"
)
data$name <- factor(
  data$name,
  levels = data$name[order(data$value)], ordered = TRUE
)

ggplot(data, aes(name, value)) + 
  geom_col() + coord_flip()

^{由 reprex 包 (v0.3.0) 于 2020-01-28 创建支持>}

^{Created on 2020-01-28 by the reprex package (v0.3.0)}

推荐答案

你可以制作一个 expression 的向量，并将其应用到 labels 参数中>scale_x_discrete:

You can make a vector of expressions, and apply it to the labels argument in scale_x_discrete:

labs <- sapply(
  strsplit(as.character(data$name), " "), 
  function(x) parse(text = paste0("italic('", x[1], "')~", x[2]))
)

ggplot(data, aes(name, value)) + 
  geom_col() + coord_flip() +
  scale_x_discrete(labels = labs)

如果您的标签中有空格，例如OTU 100，您可能想用波浪号代替空格，例如OTU~100.

If you have spaces in your labels e.g. OTU 100, you may want to substitute a tilde for the space, e.g. OTU~100.

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