[Rd] (NA || x) and (NA && y) {another "bug" } (PR#749)
maechler@stat.math.ethz.ch
maechler@stat.math.ethz.ch
Mon, 27 Nov 2000 09:25:48 +0100 (MET)
>>>>> "TL" == Thomas Lumley <thomas@biostat.washington.edu> writes:
on Subject: Re: [Rd] Problem with NAs using chisq.test() (PR#748)
which I've changed, since it is another bug we are talking about now
TL> On Sun, 26 Nov 2000 kjetikj@astro.uio.no wrote:
>> Full_Name: Kjetil Kjernsmo
..............
..............
TL> However, it would also be reasonable for NA || B to evaluate B and
TL> return TRUE or NA depending on the value. This is what S-PLUS 5
TL> does, so at least it's an incompatibility.
TL> The R documentation says
TL>> The longer form [ie ||] evaluates left to right examining only the
TL>> first element of each vector. Evaluation
TL>> proceeds only until the result is determined.
TL> which at least seems incomplete as NA | TRUE gives TRUE, but
TL> NA || TRUE gives an error.
Looks over-cautious to me as well.
We should reach a conclusion here, asap [to be effective for R 1.2].
Either
1) NA || x
(and NA && y )
continue to give errors, and we should strongly emphasize it in the
documentation -- and in the FAQ list of differences to S
or
2) really do the same as S, not only Splus 5.x, but also 3.4 which used to
be our prototype, namely
> NA || TRUE
[1] TRUE
> NA && FALSE
[1] FALSE
> NA && TRUE
[1] NA
> NA || FALSE
[1] NA
The advantage of "1)" is to catch programming errors early in some cases,
however for consistency (with "|" and "&") and compatibility,
I'm voting for a change to "2)" behaviour.
---
Martin Maechler <maechler@stat.math.ethz.ch> http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum LEO D10 Leonhardstr. 27
ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND
phone: x-41-1-632-3408 fax: ...-1228 <><
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