Adding greek symbols to legend ggplot (more than one)

Question

This thread has lead me to this nice wiki on adding greek symbols in ggplot. The code below gives alpha and beta a value in the legend. What do I have to do if I want to add more than one greek symbol for the same data point in the legend? For example "alpha =1, gamma = 2"?

d <- data.frame(x=1:10,y=1:10,f=rep(c("alpha","beta"),each=5), stringsAsFactors=FALSE)

value <- 3.1415
my.labs <- list(bquote(alpha==.(value)),bquote(beta==.(value)))

qplot(x,y,data=d,colour=f) +
  scale_colour_manual(values=1:2,breaks=c("alpha","beta"),
                      labels=my.labs)

score 3 · Answer 1 · answered Oct 29 '20 at 13:31

3

You could just pass them directly as strings using unicode escapes

my.labs <- c("\u03b1 = 1, \u03b3 = 1", paste("\u03b2 =", value))

qplot(x,y,data=d,colour=f) +
  scale_colour_manual(values=1:2, breaks=c("alpha","beta"),
                      labels=my.labs)

answered Oct 29 '20 at 13:31

Allan Cameron

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Great! However how do you know the string codes for the symbols? – tomka Oct 29 '20 at 13:32
1

@tomka Google "unicode alpha" and use the hexadecimal in front of a `\u` - the Greek letters are all sequential – Allan Cameron Oct 29 '20 at 13:33

Duck · Accepted Answer · 2020-10-29T13:34:11.627

2

Maybe this. You can smartly use paste() to concatenate the elements and add the , using expression() function:

library(ggplot2)
#Code
d <- data.frame(x=1:10,y=1:10,f=rep(c("alpha","beta"),each=5), stringsAsFactors=FALSE)
value <- 3.1415
my.labs <- c(expression(paste(alpha==1,',',~gamma==2)),expression(beta))
#Plot
qplot(x,y,data=d,colour=f) +
  scale_colour_manual(values=1:2,breaks=c("alpha","beta"),
                      labels=my.labs)

Output:

edited Oct 29 '20 at 13:34

answered Oct 29 '20 at 13:29

Duck

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Interesting (+1) but lacks a comma or separator I think – tomka Oct 29 '20 at 13:31

Adding greek symbols to legend ggplot (more than one)

2 Answers2