add 2 plots in r code example

Example: plot multiple plots in r

# One figure in row 1 and two figures in row 2
# row 1 is 1/3 the height of row 2
# column 2 is 1/4 the width of the column 1
attach(mtcars)
layout(matrix(c(1,1,2,3), 2, 2, byrow = TRUE),
   widths=c(3,1), heights=c(1,2))
hist(wt)
hist(mpg)
hist(disp)