How can I add significance letters to a plot in ggplot2, from a pairwise permutation test?

OK, so I have a plot called "meanplot", where its' x-axis is a factor category called "Group" - "Open", "South", "North. y-axis has numeric values, and called "ms".

I've added geom_jitter() for the jitter, and also geom_pointrange, which was mapped to a different df that has means and YEs, and it shows 3 points - one for each factor on x-axis.

Now I'd like to add the significance letters on top, taken from a pairwise permutation test.

The test code goes as follows:

pwpmtest <- pairwisePermutationTest(ms ~ Plot.Type,
                             data = arranged_data,
                             method="fdr")

and then I made a list, that goes:

siglist <- cldList(p.adjust ~ Comparison,
        data = pwpmtest,
        threshold  = 0.05)

which gives out this output:

> siglist
  Group Letter MonoLetter
1 North      a        a  
2  Open      b         b 
3 South      c          c

Then I tried making a plot:

letterplot <- meanplot + geom_text(data = siglist,
                                   aes(label=siglist$MonoLetter, x=Group, y=16))

And the plot I get is the same plot as before, no text. How can I fix this?

Also, can I change the order of letters in the 'siglist'? I'd love to be able to make "Open" "a", "South" "b", and "North" "c".

TIA!

Solution

Knowing exactly what you are looking for is difficult without a reproducible example. Here's something that may help, I re-created your data and made up some to fill in where you omitted information.

siglist <- tibble(Group=c("North","Open","South"),
                  Letter=c('a','b','c'),
                  MonoLetter=c('a','b','c'))

toydat <- tibble(x=c("North","Open","South"),
                 y=c(4,7,3))

ggplot() +
  geom_point(data = toydat,
             aes(x=x,y=y)) +
  geom_text(data = siglist,
            aes(x=Group,y=10,label=Letter))