[R] Plot label axis with expression

[David Winsemius]

On Aug 22, 2012, at 2:46 PM, Noia Raindrops wrote:

> Hello,
>
> Use 'parse' for converting from character to expression:
>
> x <- c(100, 50, 10, 1, 0.1, 0.05, 0.001)
> plot(log(x), yaxt = "n")
>
> parse(text = sprintf("e^%d", axTicks(2)))
> ## expression(e^-6, e^-4, e^-2, e^0, e^2, e^4)
>
> axis(2, at = axTicks(2), labels = parse(text = sprintf("e^%d",  
> axTicks(2))), las = 1)

Here's a "parse-free" approach:

axis(2, at = axTicks(2), labels =
               as.expression( sapply( axTicks(2), function(x)  
bquote(e^.(x)))),
         las = 1)

I have not found a case that makes one approach superior, although  
there seems to be an avoid-parse sentiment abroad in the R-cognoscenti.
-- 

David Winsemius, MD
Alameda, CA, USA