How to fix problem with "for" in the ggplot2 label

Question

I'm trying to make a plot with facets and add annotations in each of the facets.

I want the annotations to look like "p for trend=0.001" like the plot such as this image.

The plot I made looks like the following:

ann_text <- data.frame(x = rep(5,6), y = rep(1,6),
                       conf.low = rep(5,6), conf.high = rep(5,6),
                       term = c('A', 'B', 'C', 'D', 'E', 'F'), 
                       pvalue = c("==0.04", "<0.001", "==0.999", "==0.999", "==0.99", "==0.99"))
ann_text$term <- factor(ann_text$term)


p <- ggplot(ann_text, aes(x = x, y = y)) +
  facet_wrap(.~term) +
    geom_text(data = ann_text, 
            aes(label=paste0(rep('italic(p)~fo~trend', 6), pvalue)), 
            parse = TRUE, size = 7)
p

I think I'm almost there, but "r" is missing in the annotation, because when I add "r", it raises the following error message.

Error in parse(text = text[[i]]) : <text>:1:14: unexpected '~'
1: italic(p)~for~
                 ^

How can I solve this problem?

Maybe you could use something along the lines of code mentioned in [this](https://stackoverflow.com/questions/11889625/annotating-text-on-individual-facet-in-ggplot2) post. — Dion Groothof, Dec 24 '21 at 11:55

score 0 · Answer 1 · answered Dec 24 '21 at 14:47

Some thoughts:

I think, that for in this case is recognized something like a function, command or operator.

And R waits for something a la: for == bla-bla, for(bla-bla) etc...

How to solve:

I tried to fix this problem with latin unicode f o r characters. But it didn't help.

But we have Cyrillic Small Letter O, ha-ha. And it helps! ;)

Your modified code:

ann_text <- data.frame(x = rep(5,6), y = rep(1,6),
                       conf.low = rep(5,6), conf.high = rep(5,6),
                       term = c('A', 'B', 'C', 'D', 'E', 'F'), 
                       pvalue = c("==0.04", "<0.001", "==0.999", "==0.999", "==0.99", "==0.99"))
ann_text$term <- factor(ann_text$term)


p <- ggplot(ann_text, aes(x = x, y = y)) +
    facet_wrap(.~term) +
    geom_text(data = ann_text, 
              aes(label=paste0(rep('italic(p)~f\U043Er~trend', 6), pvalue)), 
              parse = TRUE, size = 7)
p

Output:

Thank you for letting me know the use of Cyrillic letters. – Amy Dec 28 '21 at 06:08 — Amy, Dec 28 '21 at 06:08

score 0 · Accepted Answer · answered Dec 24 '21 at 16:01

Use double quotes inside the single-quoted expression to specify the character string you do not want interpreted as code. Incidentally, you do not need to use rep() because paste0() is vectorized and will apply the 'italic(p)~"for trend"' part to however many pvalue elements there are. So, like this:

p <- ggplot(ann_text, aes(x = x, y = y)) +
  facet_wrap(.~term) +
    geom_text(data = ann_text, 
            aes(label=paste0('italic(p)~"for trend"', pvalue)), 
            parse = TRUE, size = 7)

p

How to fix problem with "for" in the ggplot2 label

2 Answers2