[External] Re: Expressions from boxplot() passed to bxp()
On Fri, 27 Mar 2020, peter dalgaard wrote:
It's not new anyway. You see the same behaviour with
boxplot(dat, ylab=quote(X[2]))
and it boils down to the use of do.call("bxp", ...) in the internals.
As a general matter, expression() exists to prevent this sort of confusion, e.g., in this construction,
X <- quote(Y+1); bquote(f(.(X)))
f(Y + 1) is indistinguishable from just entering f(Y+1), so f has no way of detecting whether or not it is intended to evaluate Y + 1. The same thing is happening with do.call: call objects are being "spliced into" the generated call, and if they are not protected with expression, you have the trouble.
do.call has a 'quote' argument that can be used to address this. The default is quote = FALSE, which means all arguments will be evaluated by the called function. Which is fine for arguments that evaluate to themselves. For symbols and calls it isn't. I did try to make the case some time ago that quote = TRUE should be the default but I lost that argument. It might be worth revisiting that, or at least reviewing the uses of do.call in our code sometime (there are a couple of hundred). Best, luke
I don't know whether it is worth trying to change this. You know the workaround. -pd
On 27 Mar 2020, at 02:55 , Marius Hofert <marius.hofert at uwaterloo.ca> wrote: Hi, Is this expected behavior (R-3.6.0)? dat <- cbind(x = 1:10, y = 10:1) ylab <- substitute(X[t], list(t = 2)) plot(dat, ylab = ylab) # works (correctly displays ylab) boxplot(dat, ylab = ylab) # fails boxplot(dat, ylab = as.expression(ylab)) # works Thanks & cheers, M
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