r plot text adding variable for text to be bolded

Question

In the example below, the variable holds the letter a. But the legend in legend just returns temp rather than a bolded a. How to make this work like it 'should'?

a <- 2
b <- 5
temp <- letters[1]
temp
plot(a,b)

legend("topleft", legend = c(as.expression(bquote(bold(get(temp)))),
                             as.expression(bquote(temp))))

like this? legend("topleft", legend = parse(text = c(sprintf('bold(%s)', temp), temp))) — rawr
– rawr, Commented Dec 7, 2022 at 22:28
Does this answer your question? using bold in mtext on string coming from vector element — divibisan
– divibisan, Commented Dec 7, 2022 at 22:28

divibisan · Accepted Answer · 2022-12-07 22:41:30Z

3

Building off the answer from here: using bold in mtext on string coming from vector element

In order to tell bquote to evaluate a variable, instead of simply printing it as text, you need to wrap the term in .(), which causes it to instead evaluate it in the specified environment (given by the where argument).

temp <- 'a'
e <- new.env()
assign('temp','b',envir = e)
plot(2,5)
legend("topleft",
       legend = c(as.expression(
           bquote(bold(temp))),                 # No .(), `temp` is text
           bquote(bold(.(temp))),               # eval `temp` in parent.env
           bquote(bold(.(temp)), where = e)))   # eval `temp` in envir "e"

The help for ?bquote mentions this:

bquote quotes its argument except that terms wrapped in .() are evaluated in the specified where environment

edited Dec 7, 2022 at 22:41

answered Dec 7, 2022 at 22:30

divibisan

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Comments

JerryN · Accepted Answer · 2022-12-14 00:18:48Z

0

The two responses helped me to get to an answer for me. I asked the question about legend. I'm using the plot functions in the terra package and the answers didn't work in the legend option in terra::plot. But this code does if you replace x and y with the relevant coordinates in your plot.

text(x, y, cex = 1.5, (bquote(paste((bold(.(a)))))))

It's extremely ungainly to look at but trying to add say a space in that string of parentheses after the 'a' for clarity didn't seem to work.

answered Dec 14, 2022 at 0:18

JerryN

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