Re: tapply not simplifying to vector? (PR#320)

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Subject: Re: tapply not simplifying to vector? (PR#320)
maechler@stat.math.ethz.ch
Date: Thu 11 Nov 1999 - 20:54:10 EST


Message-Id: <199911111054.LAA01914@pubhealth.ku.dk>

>>>>> "MatW" == Matthew Wiener <mcw@ln.nimh.nih.gov> writes:

MatW> The help file for tapply says that if simplify is true, and the
MatW> result of the calculation is always a scalar, then tapply will
MatW> return a vector.

MatW> Nonetheless:

>> t1 <- tapply(runif(10), rep(1:5, 2), mean)
>> is.vector(t1)
R> [1] FALSE
>> is.array(t1)
R> [1] TRUE

    <....>

all correct.

The question really is if the bug is in the code or the documentation.

Here you get a 1D array, something quite rare (but appearing more and more
in recent discussions...).

One could argue that the current behavior of tapply() to always return an
array if simplify = TRUE is more consistent, than what the doc says should
happen (coercing 1D arrays to vectors).
Otoh, the protoype *does* return a vector in this case,
and 1D arrays can be a pain... in other places.

I'm pro fixing this.
and I'll do if I don't hear protests..

MatW> <....>

MatW> Hope this report helps.

yes indeed, thank you!
R's quality is growing partly because of such fine bug reports!

MatW> Thanks for the terrific software.

you're welcome!

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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