之前写过一篇文档来介绍如何给标签添加特殊字符，近来有朋友需要画图正好又遇到更加复杂的需求，索性来一篇文档对此进行归纳总结，后台回复2021-6-5获取本文代码；喜欢的小伙伴欢迎扫描文末二维码加入我的交流群，更多精彩内容为您而准备
之前的方法通过bquote函数进行特殊字符格式的添加，如下所示
iris %>% as_tibble() %>%
ggplot(aes(Sepal.Length,Sepal.Width,fill=Species))
geom_point(size=4,pch=21,color="white")
xlab(bquote(Assimilation (mu~ mol ~CO[2]~ m^-2~s^-1)))
theme_classic()
如果我们需要在图中添加特殊字符该如何进行操作，同时给不同字符加以不同颜色又该如何进行设置，ggtext的出现很好的解决了这一问题
通过字符编号添加特殊字符
代码语言：javascript复制iris %>% as_tibble() %>%
ggplot(aes(Sepal.Length,Sepal.Width,fill=Species))
geom_point(size=4,pch=21,color="white")
theme_classic()
labs(x="Assimilation(u03bc molCO<sub>2</sub>m<sup>-2s</sup>-1)",
y=NULL)
theme(axis.title.x = element_markdown(color="#3B9AB2",vjust=0.5))
代码语言：javascript复制可以看到通过u03bc 此字符编号添加了特殊字符，那么有没有其它的方法呢，当然有请继续往下看
iris %>% as_tibble() %>%
ggplot(aes(Sepal.Length,Sepal.Width,fill=Species))
geom_point(size=4,pch=21,color="white")
theme_classic()
labs(title="TEST μ",
x="Assimilation(<span style='color:#F98400;'>
μ</span>molCO<sub>2</sub>m<sup>-2s</sup>-1)",
y="<span style='color:#F98400;'>αβ</span>")
theme(plot.title=element_markdown(),
axis.title.x = element_markdown(color="#3B9AB2"),
axis.title.y = element_markdown())
此图通过另外一种方式添加了特殊字符，也对部分字符颜色进行了定义，那同样我们也可以对字体大小等进行定义
下面展示一个小细节，此处含有端倪
可以看到我们将Y轴文本移至了右边，因此标签也需要定义到右边axis.title.y.right
ggplot(data.frame(x = c(-5, 5)), aes(x))
stat_function(fun = ~ .x*.x)
labs(
x = "independent variable *x*",
y = "dependent variable *y* = *x*<sup>2</sup>"
)
scale_y_continuous(position = "right")
theme(
axis.title = element_text(color = "#0072B2",
size = rel(1)),
axis.title.x = element_markdown(),
axis.title.y.right = element_markdown()
)
经上面的介绍特殊字符的添加已经变得非常容易了，但是有没有发现所展示的案例基本都是在图形外部添加字符，有时我们也需要在图内部添加一些特殊字符，因此这一部分也很重要
内部添加特殊字符
定义字符位置信息
代码语言：javascript复制df <- tibble(
label = c("SiO<sub>4</sub><sup>4-",
"NO<sup>2-","μ",
"αβ","R<sup>2</sup>=0.001",
"p_value< 2.1e<sup>-16</sup>"),
x = c(4.8,4.8,8,7,6.5,7.5),
y = c(4.1,4.3,2.3,4.2,4,4),
angle=c(0,10,0,0,0,0),
color= c("black","blue","black","red","green","black"))
添加文本
代码语言：javascript复制iris %>% as_tibble() %>%
ggplot(aes(Sepal.Length,Sepal.Width,fill=Species))
geom_point(size=4,pch=21,color="white")
theme_classic()
labs(x="Assimilation(u03bc molCO<sub>2</sub>m<sup>-2s</sup>-1)",
y=NULL)
theme(axis.title.x = element_markdown(color="#3B9AB2",vjust=0.5))
geom_richtext(data=df,aes(x,y,label=label,angle=angle,color=color),
fill=NA,label.color=NA,show.legend = F)
文本添加边框
代码语言：javascript复制iris %>% as_tibble() %>%
ggplot(aes(Sepal.Length,Sepal.Width,fill=Species))
geom_point(size=4,pch=21,color="white",show.legend = F)
theme_classic()
labs(x="Assimilation(u03bc molCO<sub>2</sub>m<sup>-2s</sup>-1)",
y=NULL)
theme(axis.title.x = element_markdown(color="#3B9AB2",vjust=0.5))
geom_richtext(data=df,aes(x,y,label=label,angle=angle),
fill=NA,show.legend = F)
添加标题
代码语言：javascript复制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 μ </i>",
virginica = "<i style='color:#009E73'>I. virginica μ </i>",
versicolor = "<i style='color:#D55E00'>I. versicolor μ </i>")
)
labs(
title = "**Fisher's *Iris* dataset(test unicode symbol: μ)**
<span style='font-size:11pt'>Sepal width vs. sepal length for three *Iris*
species μ </span>")
theme_minimal()
theme(
plot.title = element_markdown(lineheight = 1.1),
legend.text = element_markdown(size = 11),
axis.title.x = element_markdown(hjust = 0.5),
axis.title.y = element_markdown(vjust = 0.5))
在上图中我们对部分字体大小及字体类型进行了设置，并进行了换行操作，此处用到了一些markdown语法
给标题更丰富的花样
代码语言：javascript复制base <- mtcars %>%
mutate(
transmission = ifelse(am == 1, "automatic", "manual")
) %>%
ggplot(aes(hp, mpg, color = transmission))
geom_point(size = 2)
scale_color_manual(
values = c(automatic = "#0072B2", manual = "#D55E00"),
guide = "none"
)
labs(
x = "Horse power",
y = "Miles per gallon (MPG)",
title = "Transmission type impacts fuel efficiency<br>
<span style = 'font-size:10pt;'>Miles per gallon (MPG) is on average higher for cars
with <span style = 'color:#0072B2;'>automatic transmission</span> than for cars with
<span style = 'color:#D55E00;'> manual transmission.</span> However, MPG generally
declines with increasing horse power.</span>"
)
theme_bw() theme(plot.title.position = "plot")
base
theme(
plot.title = element_textbox_simple(
size = 14, lineheight = 1, padding = margin(0, 0, 5, 0)
)
)
给标题添加边框
代码语言：javascript复制base
theme(
plot.title = element_textbox_simple(
size = 14, lineheight = 1,
linetype = 1,
box.color = "#748696",
fill = "#F0F7FF",
r = grid::unit(3, "pt"),
padding = margin(5, 5, 5, 5),
margin = margin(0, 0, 10, 0)
)
)
控制边框位置
代码语言：javascript复制base
theme(
plot.title = element_textbox_simple(
size = 14, lineheight = 1,
width = grid::unit(4, "in"),
hjust = 1,
linetype = 1,
box.color = "#748696",
fill = "#F0F7FF",
r = grid::unit(3, "pt"),
padding = margin(5, 5, 5, 5),
margin = margin(0, 0, 10, 0)
)
)
