How to Label Distributions in ggplot

Question

I have the following graph of the exponential distribution, I want to put a caption showing which parameter of my exponential.

ggplot(data.frame(x=c(0,5)),aes(x))+
  stat_function(fun=dexp,colour='red',size=1.4)+
  stat_function(fun=dexp,args=list(rate=.5),colour='deepskyblue1',size=1.4)+
  stat_function(fun=dexp,args=list(rate=.75),colour='goldenrod2',size=1.4)

Answer 1

You have to put the colors as an aesthetic (within the aes). And if you want to use these specific colors ('red', 'deepskyblue1', 'goldenrod2'), they have to be passed as parameters in the scale_color_manual:

ggplot(data.frame(x=c(0,5)),aes(x))+ 
  stat_function(fun=dexp, aes(colour='1'),size=1.4)+ 
  stat_function(fun=dexp,args=list(rate=.5), aes(colour='0.5'),size=1.4)+ 
  stat_function(fun=dexp,args=list(rate=.75), aes(colour='0.75'),size=1.4) +
  scale_color_manual("Rate",values = c('red', 'deepskyblue1', 'goldenrod2'))