A histogram displays the distribution of a numeric variable. This posts explains how to add a boxplot on top of a histogram in Basic R, without any package.
            This example illustrates how to split the plotting window in base R
            thanks to the layout function. Contrary to the
            par(mfrow=...) solution, layout() allows
            greater control of panel parts.
          
Here a boxplot is added on top of the histogram, allowing to quickly observe summary statistics of the distribution.
            
          
# Create data 
my_variable=c(rnorm(1000 , 0 , 2) , rnorm(1000 , 9 , 2))
 
# Layout to split the screen
layout(mat = matrix(c(1,2),2,1, byrow=TRUE),  height = c(1,8))
 
# Draw the boxplot and the histogram 
par(mar=c(0, 3.1, 1.1, 2.1))
boxplot(my_variable , horizontal=TRUE , ylim=c(-10,20), xaxt="n" , col=rgb(0.8,0.8,0,0.5) , frame=F)
par(mar=c(4, 3.1, 1.1, 2.1))
hist(my_variable , breaks=40 , col=rgb(0.2,0.8,0.5,0.5) , border=F , main="" , xlab="value of the variable", xlim=c(-10,20))
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