[Rd] Argument recycling in substring()
Martin Maechler
maechler at stat.math.ethz.ch
Fri Jun 4 11:46:29 CEST 2010
>>>>> "HP" == Hervé Pagès <hpages at fhcrc.org>
>>>>> on Thu, 03 Jun 2010 17:53:33 -0700 writes:
HP> Hi,
HP> According to its man page substring() "expands (its) arguments
HP> cyclically to the length of the longest _provided_ none are of
HP> zero length".
HP> So, as expected, I get an error here:
>> substring("abcd", first=2L, last=integer(0))
HP> Error in substring("abcd", first = 2L, last = integer(0)) :
HP> invalid substring argument(s)
HP> But I don't get one here:
>> substring(character(0), first=1:2, last=3L)
HP> character(0)
HP> which is unexpected.
according to the docu.
My gut feeling would say that the documentation should be
updated in this case, rather than the implementation.
RFC! other opinions?
HP> Otherwise, yes substring() will recycle its arguments to the
HP> length of the longest:
>> substring("abcd", first=1:3, last=4:3)
HP> [1] "abcd" "bc" "cd"
HP> Cheers,
HP> H.
HP> --
HP> Hervé Pagès
HP> Program in Computational Biology
HP> Division of Public Health Sciences
HP> Fred Hutchinson Cancer Research Center
HP> 1100 Fairview Ave. N, M2-B876
HP> P.O. Box 19024
HP> Seattle, WA 98109-1024
HP> E-mail: hpages at fhcrc.org
HP> Phone: (206) 667-5791
HP> Fax: (206) 667-1319
HP> ______________________________________________
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