On Wed, 30 Jul 2008, Martin Maechler wrote:
"RobMcG" == McGehee, Robert <[EMAIL PROTECTED]>
on Tue, 29 Jul 2008 15:40:37 -0400 writes:
RobMcG> FYI,
RobMcG> I've tried posting the below message twice to the bug tracking
system,
[....... r-bugs problems discussed in a separate thread ....]
RobMcG> R-developers,
RobMcG> The results below are inconsistent. From the documentation for
RobMcG> is.numeric, I expect FALSE in both cases.
>> x <- data.frame(dt=Sys.Date())
>> is.numeric(x$dt)
RobMcG> [1] FALSE
>> sapply(x, is.numeric)
RobMcG> dt
RobMcG> TRUE
RobMcG> ## Yet, sapply seems aware of the Date class
>> sapply(x, class)
RobMcG> dt
RobMcG> "Date"
Yes, thanks a lot, Robert, for the report.
That *is* a bug somewhere in the .Internal(lapply(...)) C code,
when S3 dispatch of primitive functions should happen.
The bug is in do_is, which uses CHAR(PRINTNAME(CAR(call))), and when
called from lapply that gives "FUN" not "is.numeric". The root cause is
the following comment
FUN = CADR(args); /* must be unevaluated for use in e.g. bquote */
and hence that the function in the *call* passed to do_is can be
unevaluated.
Here's an R scriptlet exposing a 2nd example
### lapply(list, FUN)
### ------------------ seems to sometimes fail for
### .Primitive S3-generic functions
(ds <- seq(from=Sys.Date(), by=1, length=4))
##[1] "2008-07-30" "2008-07-31" "2008-08-01" "2008-08-02"
ll <- list(d=ds)
lapply(list(d=ds), round)
## -> Error in lapply(list(d = ds), round) : dispatch error
And that's a separate issue, in DispatchGroup which states that arguments
have been evaluated (true) but the 'call' from lapply gives the
unevaluated arguments and so there is a mismatch.
I'm testing fixes for both.
## or -- related to bug report by Robert McGehee on R-devel, on 2008-07-29:
sapply(list(d=ds), is.numeric)
## TRUE
## in spite of
is.numeric(`[[`(ll,1)) ## FALSE , because of
is.numeric.date
## or
round(`[[`(ll,1))
## [1] "2008-07-30" "2008-07-31" "2008-08-01" "2008-08-02"
##-----------------------------
But I'm currently too much tied up with other duties,
to find and test bug-fix.
Martin Maechler, ETH Zurich and R-Core Team
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--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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