Only the stripped down density plot appears in the output:

library(ggplot2)
library(cowplot)

raises <- attitude$raises
df <- data.frame(raises)

ph <- ggplot(df, aes(x = raises))  
  geom_histogram(binwidth = 1, color = "black", fill = "light grey")  
  scale_x_continuous(breaks = seq(40, 90, by = 10))  
  ylim(0,3)  
  theme_classic()

pd <- ggplot(df, aes(x = raises))  
  geom_density()  
  scale_x_continuous(breaks = seq(40, 90, by = 10))  
  scale_y_continuous(expand = expansion(mult = c(0, 0.1)), position = "right")  
  theme_classic()  
  theme(axis.line.x = element_blank(),
        axis.title.x = element_blank(),
        axis.text.x = element_blank(),
        axis.ticks.x = element_blank())

alpl <- align_plots(ph, pd, align = "hv", axis = "tblr")
ggdraw(alpl[[1]])   draw_plot(alpl[[2]])

I would like to overlay them so that you can see the histogram with the frequency as well as the density.

CodePudding user response：

You have an opaque plot background and panel background in your density plot which you need to remove in theme. Obviously, I don't have your data, but the following code gives you the idea:

library(ggplot2)
library(cowplot)

set.seed(1)

df <- data.frame(raises = c(rnorm(100, 65, 10)))

ph <- ggplot(df, aes(x = raises))  
  geom_histogram(binwidth = 1, color = "black", fill = "light grey")  
  scale_x_continuous(breaks = seq(40, 90, by = 10), limits = c(40, 90))  
  ylim(0,3)  
  theme_classic()

pd <- ggplot(df, aes(x = raises))  
  geom_density()  
  scale_x_continuous(breaks = seq(40, 90, by = 10), limits = c(40, 90))  
  scale_y_continuous(expand = expansion(mult = c(0, 0.1)), position = "right")  
  theme_classic()  
  theme(axis.line.x = element_blank(),
        axis.title.x = element_blank(),
        axis.text.x = element_blank(),
        axis.ticks.x = element_blank(),
        plot.background = element_blank(),
        panel.background = element_blank())

alpl <- align_plots(ph, pd, align = "hv", axis = "tblr")
ggdraw(alpl[[1]])   draw_plot(alpl[[2]])