R语言之可视化（32）之ggtext：提高ggplot2的文本呈现

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发布于 2020-05-18 15:38:08

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发布于 2020-05-18 15:38:08

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R语言之可视化（31）扫地僧easystats（2）相关性分析

该ggtext软件包为ggplot2 提供了富文本（基本HTML和Markdown）支持。富文本可用于图注解（图标题，字幕，标题，轴标签，图例等）中并可视化文本数据，就像通常使用geom_text（）。

安装包

remotes::install_github("wilkelab/ggtext")

该软件包在CRAN上可用后，您将可以照常通过install.packages（）安装最新版本。

install.packages("ggtext")

示例

所有文本渲染都是通过gridtext软件包中的richtext_grob（）或textbox_grob（）来执行的。ggtext包定义了两个新的主题元素，element_markdown（）和element_textbox（）。两者的行为都类似于element_text（），但将提供的文本呈现为markdown / html。 element_markdown（）是element_text（）的直接替代，它呈现文本而无需自动换行。要开始新行，请使用标记或在行尾之前添加两个空格。

library(ggplot2)
library(ggtext)

ggplot(iris, aes(Sepal.Length, Sepal.Width, color = Species)) +
  geom_point(size = 3) +
  scale_color_manual(
    name = NULL,
    values = c(setosa = "#0072B2", virginica = "#009E73", versicolor = "#D55E00"),
    labels = c(
      setosa = "<i style='color:#0072B2'>I. setosa</i>",
      virginica = "<i style='color:#009E73'>I. virginica</i>",
      versicolor = "<i style='color:#D55E00'>I. versicolor</i>")
  ) +
  labs(
    title = "**Fisher's *Iris* dataset**  
    <span style='font-size:11pt'>Sepal width vs. sepal length for three *Iris*
    species</span>",
    x = "Sepal length (cm)", y = "Sepal width (cm)"
  ) +
  theme_minimal() +
  theme(
    plot.title = element_markdown(lineheight = 1.1),
    legend.text = element_markdown(size = 11)
  )

image

可以使用它来将图像用作轴标签。

labels <- c(
  setosa = "<img src='https://upload.wikimedia.org/wikipedia/commons/thumb/8/86/Iris_setosa.JPG/180px-Iris_setosa.JPG'
    width='100' /><br>*I. setosa*",
  virginica = "<img src='https://upload.wikimedia.org/wikipedia/commons/thumb/3/38/Iris_virginica_-_NRCS.jpg/320px-Iris_virginica_-_NRCS.jpg'
    width='100' /><br>*I. virginica*",
  versicolor = "<img src='https://upload.wikimedia.org/wikipedia/commons/thumb/2/27/20140427Iris_versicolor1.jpg/320px-20140427Iris_versicolor1.jpg'
    width='100' /><br>*I. versicolor*"
)

ggplot(iris, aes(Species, Sepal.Width)) +
  geom_boxplot() +
  scale_x_discrete(
    name = NULL,
    labels = labels
  ) +
  theme(
    axis.text.x = element_markdown(color = "black", size = 11)
  )

element_textbox（）提供了对渲染大量需要自动换行的文本的支持。与element_markdown（）不同，它不能用于轴刻度标签，也不能以任意角度绘制文本，只能以对应于0、90、180和270度的固定方向绘制文本。实际上，您通常希望使用element_textbox_simple（）而不是element_textbox（），因为它为ggplot2主题中通常未定义的许多参数设置了有用的默认值。

ggplot(mtcars, aes(disp, mpg)) + 
  geom_point() +
  labs(
    title = "<b>Fuel economy vs. engine displacement</b><br>
    <span style = 'font-size:10pt'>Lorem ipsum *dolor sit amet,*
    consectetur adipiscing elit, **sed do eiusmod tempor incididunt** ut
    labore et dolore magna aliqua. <span style = 'color:red;'>Ut enim
    ad minim veniam,</span> quis nostrud exercitation ullamco laboris nisi
    ut aliquip ex ea commodo consequat.</span>",
    x = "displacement (in<sup>3</sup>)",
    y = "Miles per gallon (mpg)<br><span style = 'font-size:8pt'>A measure of
    the car's fuel efficiency.</span>"
  ) +
  theme(
    plot.title.position = "plot",
    plot.title = element_textbox_simple(
      size = 13,
      lineheight = 1,
      padding = margin(5.5, 5.5, 5.5, 5.5),
      margin = margin(0, 0, 5.5, 0),
      fill = "cornsilk"
    ),
    axis.title.x = element_textbox_simple(
      width = NULL,
      padding = margin(4, 4, 4, 4),
      margin = margin(4, 0, 0, 0),
      linetype = 1,
      r = grid::unit(8, "pt"),
      fill = "azure1"
    ),
    axis.title.y = element_textbox_simple(
      hjust = 0,
      orientation = "left-rotated",
      minwidth = unit(1, "in"),
      maxwidth = unit(2, "in"),
      padding = margin(4, 4, 2, 4),
      margin = margin(0, 0, 2, 0),
      fill = "lightsteelblue1"
    )
  )

另一个示例，用文本框替换facet。

library(cowplot)

ggplot(mpg, aes(cty, hwy)) + 
  geom_point() +
  facet_wrap(~class) +
  theme_half_open(12) +
  background_grid() +
  theme(
    strip.background = element_blank(),
    strip.text = element_textbox(
      size = 12,
      color = "white", fill = "#5D729D", box.color = "#4A618C",
      halign = 0.5, linetype = 1, r = unit(5, "pt"), width = unit(1, "npc"),
      padding = margin(2, 0, 1, 0), margin = margin(3, 3, 3, 3)
    )
  )

image

geom_richtext（）提供markdown / html标签。与geom_label（）不同，标签可以旋转。

df <- data.frame(
  label = c(
    "Some text **in bold.**",
    "Linebreaks<br>Linebreaks<br>Linebreaks",
    "*x*<sup>2</sup> + 5*x* + *C*<sub>*i*</sub>",
    "Some <span style='color:blue'>blue text **in bold.**</span><br>And *italics text.*<br>
    And some <span style='font-size:18pt; color:black'>large</span> text."
  ),
  x = c(.2, .1, .5, .9),
  y = c(.8, .4, .1, .5),
  hjust = c(0.5, 0, 0, 1),
  vjust = c(0.5, 1, 0, 0.5),
  angle = c(0, 0, 45, -45),
  color = c("black", "blue", "black", "red"),
  fill = c("cornsilk", "white", "lightblue1", "white")
)

ggplot(df) +
  aes(
    x, y, label = label, angle = angle, color = color, fill = fill,
    hjust = hjust, vjust = vjust
  ) +
  geom_richtext() +
  geom_point(color = "black", size = 2) +
  scale_color_identity() +
  scale_fill_identity() +
  xlim(0, 1) + ylim(0, 1)

image

没有框架或背景的标签也是可以的。

ggplot(df) +
  aes(
    x, y, label = label, angle = angle, color = color,
    hjust = hjust, vjust = vjust
  ) +
  geom_richtext(
    fill = NA, label.color = NA, # remove background and outline
    label.padding = grid::unit(rep(0, 4), "pt") # remove padding
  ) +
  geom_point(color = "black", size = 2) +
  scale_color_identity() +
  xlim(0, 1) + ylim(0, 1)

df <- data.frame(
  label = rep("Lorem ipsum dolor **sit amet,** consectetur adipiscing elit,
    sed do *eiusmod tempor incididunt* ut labore et dolore magna
    aliqua.", 2),
  x = c(0, .6),
  y = c(1, .6),
  hjust = c(0, 0),
  vjust = c(1, 0),
  orientation = c("upright", "right-rotated"),
  color = c("black", "blue"),
  fill = c("cornsilk", "white")
)

ggplot(df) +
  aes(
    x, y, label = label, color = color, fill = fill,
    hjust = hjust, vjust = vjust,
    orientation = orientation
  ) +
  geom_textbox(width = unit(0.4, "npc")) +
  geom_point(color = "black", size = 2) +
  scale_discrete_identity(aesthetics = c("color", "fill", "orientation")) +
  xlim(0, 1) + ylim(0, 1)