Grouped densities over histogram - how to remove density marker from legend? (Ggplot, R)-CodePudding

Reproducible example:

require(ggplot2)

mtcars$am2 <- factor(mtcars$am)
p1 <- ggplot(mtcars, aes(x = mpg, y = ..density.., fill = am2))  
  geom_histogram(position = "identity", alpha = 0.8, colour = 1, bins = 12) 
  scale_fill_manual(values = c( "pink", "lightgrey"))  
  theme(
    legend.position = "bottom"
  )

p1  
  geom_density(colour = "blue", lwd = 2, inherit.aes = F, aes(x = mpg, y = ..density.., group = am2))

I would like to remove the thick blue border from around the squares representing the colours in the legend. (In my real data this makes sense, the two densities don't overlap.) I have tried to play with legend.key = this and that in theme(), but nothing seems to take effect. Can anyone help, please?

CodePudding user response：

You could use show.legend=FALSE in your geom_density call to remove the blue border in your legend like this:

mtcars$am2 <- factor(mtcars$am)
library(ggplot2)
p1 <- ggplot(mtcars, aes(x = mpg, y = ..density.., fill = am2))  
  geom_histogram(position = "identity", alpha = 0.8, colour = 1, bins = 12) 
  scale_fill_manual(values = c( "pink", "lightgrey"))  
  theme(legend.position = "bottom") 

p1  
  geom_density(colour = "blue", lwd = 2, inherit.aes = F, aes(x = mpg, y = ..density.., group = am2), show.legend = FALSE)

^{Created on 2022-10-15 with reprex v2.0.2}

CodePudding user response：

Add show_guide = FALSE in geom_density:

mtcars$am2 <- factor(mtcars$am)
p1 <- ggplot(mtcars, aes(x = mpg, y = ..density.., fill = am2))  
  geom_histogram(position = "identity", alpha = 0.8, colour = 1, bins = 12) 
  scale_fill_manual(values = c( "pink", "lightgrey"))  
  theme(
    legend.position = "bottom"
  )

p1  
  geom_density(colour = "blue", lwd = 2, inherit.aes = F, show_guide = FALSE, aes(x = mpg, y = ..density.., group = am2))