如何在R中的多个图传奇条目中添加度数符号？

Question

I know I can add a degree symbol to a plot legend by using expression .

plot(1:5,1:5)
legend('topleft', fill = 'white', legend = expression(5~degree~C))

But How can I do this for multiple legend entries?

I tried the following, but it didn't work:

plot(1:5,1:5)
points(1:5,(1:5) + 0.1, col = 2)
legend('topleft', fill = c('white','red'), legend = paste0(c(5,10), expression(~degree~C)))

Edit: I am more interested in how to do this for many values, not just 2.

Any suggestions on how to do this succinctly and neatly would be greatly appreciated! Thanks!

Answer 1

I think you need the help of substitute and expression . You do a sapply of the vector for which you need to write the expression, here i am putting c(5,10) as input of sapply. For the function part, you need to use as.expression with substitute.

plot(1:5,1:5)
points(1:5,(1:5) + 0.1, col = 2)
legend('topleft', fill = c('white','red'), legend = sapply(c(5,10), function(x) as.expression(substitute(A~degree~"C",list(A = as.name(x))))))

Output :

Answer 2

您可以在表达式中包含这两个值

  legend('topleft', fill = c('white','red'), expression(5~degree~C,10~degree~C))

Answer 3

对于ggplot：

ylab(expression(paste("SST (",degree~C,")"))) +