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
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文本该如何进行操作，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
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 molCO2m-2s-1)",
y=NULL)+
theme(axis.title.x = element_markdown(color="#3B9AB2",vjust=0.5))
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(
μmolCO2m-2s-1)",
y="αβ")+
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*2"
) +
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这些特殊字符，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
df <- tibble(
label = c("SiO44-",
"NO2-","μ",
"αβ","R2=0.001",
"p_value< 2.1e-16"),
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
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 molCO2m-2s-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
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 molCO2m-2s-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
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. setosa μ ",
virginica = "I. virginica μ ",
versicolor = "I. versicolor μ ")
) +
labs(
title = "**Fisher's *Iris* dataset(test unicode symbol: μ)**
Sepal width vs. sepal length for three *Iris*
species μ ") +
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
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
Miles per gallon (MPG) is on average higher for cars
with automatic transmission than for cars with
manual transmission. However, MPG generally
declines with increasing horse power."
) +
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
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
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)
)
)
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R语言数据分析指南，持续分享数据可视化的经典案例及一些生信知识，希望对大家有所帮助