ggplot2爲幾個stat_functions添加圖例

Question

我看到很多關於如何自定義圖例的問題，但我甚至無法獲取圖例來自定義。我希望有一個傳說解釋黑線是二次的，綠線是立方。

library(ggplot2) 

myfun1 <- function(x) x^2 
myfun2 <- function(x) x^3 

myplot <- ggplot(data = data.frame(x = 1:5, y= 1:5), aes(x=x, y=y)) + 
    stat_function(fun = myfun1, color="green") + 
    stat_function(fun = myfun2, color="black") 

Answer 1

試試這個：

ggplot(NULL, aes(x=x, colour = g)) + 
    stat_function(data = data.frame(x = 1:5, g = factor(1)), fun = myfun1) + 
    stat_function(data = data.frame(x = 1:5, g = factor(2)), fun = myfun2) + 
    scale_colour_manual(values = c("red", "green"), labels = c("quadratic", "cubic"))