Question

Consider the following example:

dat <- matrix(rexp(240, rate=.1), ncol=6)
par(mfrow=c(3,2))

for (i in 1:6){
    plot(dat[,i],xlab = "Day of year",col = "black",
         ylab = expression(paste("Temperature ",degree,"C")))
  }

This produces 6 subplots where the x and y label are clearly shown.

I would like to alter this so that the ylabel is only shown on the panels which are on the right (to avoid repetition). So, I write:

for (i in 1:6){
  if (i %% 2 == 0){
    plot(dat[,i],ylab = "",xlab = "Day of year",col = "black")
  }
  else {plot(dat[,i],ylab = expression(paste("Temperature ",degree,"C")),
             xlab = "Day of year",col = "black")
  }
}

Which produces:

Where we can see that only the even numbered panel now have the ylabel. I would also like to have the figure so that only panel 5 and 6 has the xlabel, which I could so by adding another if statement. However, it seems a lot of work to do something so simple. Can anyone suggest an alternative method. As I am a beginner with R I would prefer to use some of the R base functions first i.e. not lattice nor ggplot. However, if there isn’t a cleaner way of doing this with the base functions, other suggestions are welcomed.

Answer 1

ifelse is a helpful shortcut.

for (i in 1:6){
    plot(dat[,i],xlab = ifelse(i %% 2 == 0,"","Day of year",col = "black",
         ylab = ifelse(i %% 2 == 0,"",expression(paste("Temperature ",degree,"C")))

Also, you can use mtext with outer=TRUE if all axes are the same. After you plot everything with no labels, try:

mtext("Day of Year", side=1, padj=-2, outer=TRUE)
mtext("Temperature", side=2, padj=2, outer=TRUE)