[R] match and incomparables

[Prof Brian Ripley]

On Fri, 12 Sep 2008, Bert Gunter wrote:

> Looks like a bug to me. Compare:

A bug fixed in the R-devel version of R (because of a related problem with 
duplicated).

>> match (1:3,1:3,incom=3)
> [1] 1 2 3
>> match (1:3,1:3,incom=2:3)
> [1] 1 2 3
>> match (1:3,1:3,incom=1:2)
> [1] NA NA  3
>> match (1:3,1:3,incom=1)
> [1] NA  2  3
>
> Cheers,
> Bert
>
>
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
> Behalf Of Adam D. I. Kramer
> Sent: Friday, September 12, 2008 3:06 PM
> To: McGehee, Robert
> Cc: r-help
> Subject: Re: [R] match and incomparables
>
> I can replicate this and also do not understand it.
>
>> match(1:3,1:3,incomparables=5)
> [1] NA  2  3
>> match(1:3,1:3,incomparables=4)
> [1] 1 2 3
>> match(1:3,1:3,incomparables=3)
> [1] 1 2 3
>> match(1:3,1:3,incomparables=2)
> [1] 1 2 3
>> match(1:3,1:3,incomparables=1)
> [1] NA  2  3
>
> ...every other integer value for incomparables produces 1 2 and 3 for
> output. I'm using R 2.7.2, self-compiled, under linux.
>
> --Adam
>
> On Fri, 12 Sep 2008, McGehee, Robert wrote:
>
>> Hello,
>> I was playing around with the newly implemented 'incomparables' argument
>> in 'match' and realized the argument does not behave anything like I
>> expected. Can someone explain what is going on here? Sorry if I'm
>> misreading the documentation.
>>
>>> match(1:3, 1:3, incomparables=1)
>> [1] NA  2  3  # This seems right, the 1 in 'x' is 'incomparable'
>>
>>> match(1:3, 1:3, incomparables=2)
>> [1] 1  2  3   # Shouldn't this be 1 NA 3? Why isn't the 2 incomparable?
>>
>>> match(1:3, 1:3, incomparables=5)
>> [1] NA  2  3   # Why isn't the 5 ignored?
>>
>> Note from ?match:
>> "incomparables: a vector of values that cannot be matched. Any value in
>> x matching a value in this vector is assigned the nomatch value. For
>> historical reasons, FALSE is equivalent to NULL."
>>
>> Thanks in advance!
>> Robert
>>
>> platform       i386-pc-mingw32
>> arch           i386
>> os             mingw32
>> system         i386, mingw32
>> status
>> major          2
>> minor          7.2
>> year           2008
>> month          08
>> day            25
>> svn rev        46428
>> language       R
>> version.string R version 2.7.2 (2008-08-25)
>>
>> Robert McGehee, CFA
>> Geode Capital Management, LLC
>> One Post Office Square, 28th Floor | Boston, MA | 02109
>> Tel: 617/392-8396    Fax:617/476-6389
>> mailto:robert.mcgehee at geodecapital.com
>>
>>
>>
>> This e-mail, and any attachments hereto, are intended fo...{{dropped:12}}
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
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