R Corrplot：斜体 Y 轴标签

Question

I have a problem that would be extremely easy to solve in ggplot , but can´t figure out how to make it work in corrplot . How to make y-axis labels in italics??

library(corrplot)
M <- cor(mtcars)
corrplot(M, method="circle") 

Answer 1

If you use font = 3 it will italicize all the axes. If you only want the Y axis, a workaround is:

par(mar = c(4, 6, 4, 4))
temp <- corrplot(M, method = "circle", font = 3, tl.pos='n',
                 mar = c(0, 0, 4, 0))
mtext(unique(temp$corrPos$yName), 
      at = unique(temp$corrPos$y), side = 2, las = 1,
      font = 3)
mtext(unique(temp$corrPos$xName), 
      at = unique(temp$corrPos$x), las = 2)

Output:

Though may need some tweaking of the margins on your end to line things up.

Answer 2

In corrplot , there is a ... argument which allows extra parameters to be passed to the base R text function. Since text has a font parameter, where the value 3 means italics, you can do:

library(corrplot)
M <- cor(mtcars)
corrplot(M, method="circle", font = 3)