I am puzzled by this (with R --vanilla):
> test <- function(formula, ...) lm(formula, ...)
> test(1:4 ~ 1, offset=rep(1,4))
Error in eval(expr, envir, enclos) : ..1 used in an incorrect
context, no ... to look in
> test(1:4 ~ 1, weights=rep(1,4))
Error in eval(expr, envir, enclos) : ..1 used in an incorrect
context, no ... to look in
> test(1:4 ~ 1, x=TRUE)
Call:
lm(formula = formula, x = TRUE)
Coefficients:
(Intercept)
2.5
Some arguments (such as x) seem to pass willingly through ..., while
others (such as offset and weights) do not. Same thing happens with
glm. I haven't experimented more widely.
Can some kind soul offer an explanation?
Thanks,
David
> version
_
platform powerpc-apple-darwin6.7.5
arch powerpc
os darwin6.7.5
system powerpc, darwin6.7.5
status
major 1
minor 8.0
year 2003
month 10
day 08
language R
matching of arguments in ...?
2 messages · David Firth, Thomas Lumley
On Wed, 5 Nov 2003, David Firth wrote:
I am puzzled by this (with R --vanilla):
> test <- function(formula, ...) lm(formula, ...) > test(1:4 ~ 1, offset=rep(1,4))
Error in eval(expr, envir, enclos) : ..1 used in an incorrect context, no ... to look in
> test(1:4 ~ 1, weights=rep(1,4))
Error in eval(expr, envir, enclos) : ..1 used in an incorrect context, no ... to look in
> test(1:4 ~ 1, x=TRUE)
Call:
lm(formula = formula, x = TRUE)
Coefficients:
(Intercept)
2.5
Some arguments (such as x) seem to pass willingly through ..., while
others (such as offset and weights) do not. Same thing happens with
glm. I haven't experimented more widely.
Can some kind soul offer an explanation?
This is a historical legacy of someone trying to be too helpful. In lm() and similar functions there are some arguments that are interpreted as if they were quoted expressions and then are looked up in data= and in the calling frame (actually in environment(formulas)). So lm(y~x, offset=z, data=df) will work if z is either a column of df or a variable floating free in the calling frame. In order to make this rather unnatural evaluation work, lm and model.frame have to play tricks with these arguments: they are explicitly evaluated in environment(formula), in this case the environment inside test(). This sort of thing is why some of us strongly recommend not having implicit dynamic scoping on new modelling functions, so eg in the survey package the syntax looks like svydesign(id=~id, weights=~w, data=df) with explicit formulas. The other option is explicitly quoted expressions. -thomas