将数学符号和下标与常规字母混合在一起 [英] Putting mathematical symbols and subscripts mixed with regular letters

问题描述

我想在ggplot2中绘制一个看起来像这样的标签:

I want to plot a label that looks like this in ggplot2:

Value is $\sigma$, R^{2} = 0.6，其中Value is是普通字体，$\sigma$是希腊小写西格玛字母，R^{2} = 0.6显示为带有上标2后跟等号(=)的R 0.6.如何在ggplot factor s和R的xlab,ylab之类的参数中使用它?

Value is $\sigma$, R^{2} = 0.6 where Value is is ordinary font, $\sigma$ is a Greek lowercase sigma letter and R^{2} = 0.6 appears as an R with a superscript 2 followed by equal sign (=) followed by 0.6. How can this be used in ggplot factors and in arguments to things like xlab,ylab of R?

推荐答案

类似这样的东西:

g <- ggplot(data=data.frame(x=0,y=0))+geom_point(aes(x=x,y=y))
g+ xlab( expression(paste("Value is ", sigma,",", R^{2},'=0.6')))

编辑

另一种选择是将annotate与parse=T一起使用:

Another option is to use annotate with parse=T:

g+ annotate('text', x = 0, y = 0, 
        label = "Value~is~sigma~R^{2}==0.6 ",parse = TRUE,size=20) 

编辑

如果在绘制过程中计算常数0.6，则paste解决方案可能会很有用.

The paste solution may be useful if the constant 0.6 is computed during plotting.

r2.value <- 0.90
g+ xlab( expression(paste("Value is ", sigma,",", R^{2},'=',r2.value)))

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