R: how to build a mathematical expression from a symbol object?

Question

In R, I want to create a graph with an x-axis label expression(varname), where varnameis the symbol object. For instance:

varname <- "beta[1]"
hist(rnorm(20),xlab=expression(varname))

But it gives me a schedule with xlab="varname", and not xlab=expression(beta[1]). How to convince to expression()evaluate a variable?

Answer 1

You can do

hist(rnorm(20),xlab=parse(text=varname))