ggplot2 argument handling odd
Ok, I will try that, thanks. BTW, where is this aes_string option documented, sounds useful? How could I do the same thing with facetting? If I want to save something like ". ~ groupVar" as a string in a variable, could I pass it with facet_string to ggplot?
It's a see also from ?aes (or at least it is in the development version). facet_grid should already accept a string instead of a function, so it should just work.
But anyway, I would be curious how to do it with qplot. The basic question is: How to pass the string of a variable to a function which is supposed to interpret it. Aka: var <- "magicVar" fun(doSomeMagic(var)) doSomeMagic should then write magicVar at the place.
In general, you can use as.name, substitute and eval:
x <- as.name("mpg")
y <- as.name("wt")
eval(substitute(qplot(x, y, data=mtcars), list(x=x, y=y)))
Hadley