stringsAsFactors param in expand.grid not working
On 19/05/2009, at 10:20 AM, Steve Lianoglou wrote:
Hi all,
I've (tried) to look through the bug tracker, and gmane-search the
R list to
see if this has been mentioned before, and it looks like it hasn't.
According to the R 2.9.0 release notes[1], the expand.grid function
should now
take a stringsAsFactor=LOGICAL argument which controls whether or
not the
function coerces strings as factors. While the parameter is indeed
in the
function, a quick examination of the function's source shows that
the value
of this argument is never checked, and all strings are converted to
factors
as a matter of course.
The fix is pretty easy, and I believe only requires changing the
`if` check
here:
if (!is.factor(x) && is.character(x))
x <- factor(x, levels = unique(x))
To:
if (!is.factor(x) && is.character(x) && stringsAsFactors)
x <- factor(x, levels = unique(x))
I can open a ticket regarding this issue and add this there if
necessary.
Thanks,
-steve
[1] http://article.gmane.org/gmane.comp.lang.r.general/146891
While we're at it --- would it not make sense to have the
stringsAsFactors
argument (once it's working) of expand.grid() default to options()
$stringsAsFactors,
rather than to FALSE?
This would make no difference to me personally, since I set
options(stringsAsFactors=FALSE) in my .Rprofile. But it might make some
people happier ....
cheers,
Rolf Turner
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