From baron@cattell.psych.upenn.edu  Fri Jan 31 18:58:48 2003
From: baron@cattell.psych.upenn.edu (Jonathan Baron)
Date: Fri Jan 31 18:58:48 2003
Subject: [Rd] minor error in documentation of pmax in base (PR#2513)
In-Reply-To: <3A822319EB35174CA3714066D590DCD534BC0D@usrymx25.merck.com>; from andy_liaw@merck.com on Fri, Jan 31, 2003 at 12:42:43PM -0500
References: <3A822319EB35174CA3714066D590DCD534BC0D@usrymx25.merck.com>
Message-ID: <20030131125423.A9921@cattell.psych.upenn.edu>

In a way it is not surprising, but some functions that operate on
vectors will coerce their outputs into vectors and others won't.
For example, try

m1 <- array(1:24,c(2,3,4))
sort(m1)
order(m1)

It would be nice to say when each of these things will happen.

For example, in the documentaition for ifelse, it says, "returns
a value with the same shape as".  This sort of language would be
helpful.

Jon

On 01/31/03 12:42, Liaw, Andy wrote:
>If I'm not mistaken, matrices and arrays are just vectors with dim
>attribute.  so I'm not surprised that pmax and pmin work as they do.  You
>get the same answer by the following:
>
>array(pmax(1:24, 24:1), c(2, 3, 4))
>array(pmin(1:24, 24:1), c(2, 3, 4))
>
>
>Cheers,
>Andy
>
>> -----Original Message-----
>> From: baron@cattell.psych.upenn.edu
>> [mailto:baron@cattell.psych.upenn.edu]
>> Sent: Friday, January 31, 2003 12:37 PM
>> To: r-devel@stat.math.ethz.ch
>> Cc: R-bugs@biostat.ku.dk
>> Subject: [Rd] minor error in documentation of pmax in base (PR#2513)
>> 
>> 
>> The documentation says, "pmax and pmin take several vectors as
>> arguments and return a single vector giving the parallel maxima
>> (or minima) of the vectors."
>> 
>> I discovered that, if you use a matrix or array instead of a
>> vector, pmax returns a matrix or array, respectively.
>> 
>> This makes pmax and pmin much more useful, and should not be left
>> to people to discover on their own!
>> 
>> For example:
>> m1 <- array(1:24,c(2,3,4))
>> m2 <- array(24:1,c(2,3,4))
>> pmax(m1,m2)
>> pmin(m1,m2)
>> 
>> Jon Baron
>> 
>> ______________________________________________
>> R-devel@stat.math.ethz.ch mailing list
>> http://www.stat.math.ethz.ch/mailman/listinfo/r-devel
>> 
>
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-- 
Jonathan Baron, Professor of Psychology, University of Pennsylvania
Home page:            http://www.sas.upenn.edu/~baron
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[Rd] minor error in documentation of pmax in base (PR#2513)
Jonathan Baron