Combining 2 normal probability plots in same ggplot-CodePudding

I have 2 normal probability plots as below

library(ggplot2)

# Plot 1
ggplot(data.frame(x = c(-4, 4)), aes(x))   
  stat_function(fun = dnorm, args = list(mean = 0, sd = 1), col='red')   
  stat_function(fill='red', fun = dnorm, xlim = c(-4, -1), geom = "area")   
  stat_function(fill='red', fun = dnorm, xlim = c(-1, 4), geom = "area", alpha = 0.3) 

# Plot 2
ggplot(data.frame(x = c(-4, 4)), aes(x))   
  stat_function(fun = dnorm, args = list(mean = 0, sd = 2), col='blue')   
  stat_function(fill='blue', fun = dnorm, args = list(mean = 0, sd = 2), xlim = c(-4, -1), geom = "area")   
  stat_function(fill='blue', fun = dnorm, args = list(mean = 0, sd = 2), xlim = c(-1, 4), geom = "area", alpha = 0.3)

Individually they are just fine. However I wanted to combine these 2 plots and place them in same plot window with same x-axis.

I also want to add a legend based on fill color in the combined plot to distinguish them.

Is there any way to achieve this with ggplot?

Any pointer will be very helpful

CodePudding user response：

You could combine both the stat_functions and create two with an aes for your fill to create a legend with scale_fill_manual like this:

library(ggplot2)
ggplot(data.frame(x = c(-4, 4)), aes(x))   
  stat_function(fun = dnorm, args = list(mean = 0, sd = 1), col='red')   
  stat_function(fun = dnorm, xlim = c(-4, -1), geom = "area", aes(fill = "plot 1"))   
  stat_function(fill='red', fun = dnorm, xlim = c(-1, 4), geom = "area", alpha = 0.3)  
  stat_function(fun = dnorm, args = list(mean = 0, sd = 2), col='blue')   
  stat_function(fun = dnorm, args = list(mean = 0, sd = 2), xlim = c(-4, -1), geom = "area", aes(fill = "plot 2"))   
  stat_function(fill='blue', fun = dnorm, args = list(mean = 0, sd = 2), xlim = c(-1, 4), geom = "area", alpha = 0.3)  
  scale_fill_manual(name = "Legend", values = c("red", "blue"))

^{Created on 2022-12-31 with reprex v2.0.2}