Question

I would like to get the latex symbol for beta with a subscript of 2.

The following code:

idx <- 2;
ylab(eval(expression(paste("beta[",idx,"]",sep=""))))

produces the label “beta[2]” instead of “\beta_{2}”. What am I doing wrong?

Note: to see what I want, just use ylab(expression(beta[2])), but I want to pull the value out of the variable idx instead of using a hard-coded value.

Answer 1

Use bquote. Here is a sample code snippet

library(ggplot2)
p1 = qplot(tip, data = tips)
idx = 2;
my.ylab = bquote(beta[2] == .(idx))
p1 + ylab(my.ylab)