在R中的ggplots中添加方程式

问题描述

我想手动将回归方程式添加到包含适当数学符号(例如，斜体，上标)的绘图中.Annotate()似乎很完美，但是似乎不接受labels参数中的expression()函数.这是一个简单的例子.带有expression()的注释将不会显示.我在做什么错了?

I'd like to manually add a regression equation to a plot that includes the proper mathematical notation (e.g., italics, superscripts). Annotate() seems perfect for this, but it doesn't seem to accept the expression() function in the labels argument. Here is a simple example. The annotation with expression() in it won't display. What am I doing wrong?

 library(ggplot2)
 x <- 1:10
 y <- x^2
 df <- data.frame(x, y)
 sp <- ggplot(df, aes(x, y)) + geom_point()
 sp + annotate('text', label = expression('y = x^2'), x = 2.5, y = 50) +
      annotate('text', label = 'y = x^2', x = 2.5, y = 75)

推荐答案

使用geom_text代替注释:

Use geom_text instead of annotate:

sp + geom_text(aes(2.5,75, label=(paste(expression("y = x "^-2*"")))),parse = TRUE)

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