[Rd] match vs. %in% (PR#853)
Prof Brian D Ripley
Mon, 19 Feb 2001 07:24:55 +0000 (GMT)
On Sun, 18 Feb 2001 firstname.lastname@example.org wrote:
> This isn't really a bug so much as an undocumented feature, but
> perhaps the help file should be changed.
> If you say
> you get the values of the _first_ instance in y that matches each
> value of x.
Yes, but one match or not for each instance of x.
> If you say
> x %in% y
> you get "TRUE" for every match, not just the first.
You get a result for each element of x, not y.
Both return a result for each element of x. match returns the index of the
first match or `nomatch', %in% returns TRUE or FALSE.
is.element is a synonym of %in% compatible with S, which uses %in% for
something else (nesting in formulae).
> This is useful, now that I know it, but perhaps the thing
> about the first instance should be documented.
Yes, ?match needs a `details' section. I'll add one.
Brian D. Ripley, email@example.com
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 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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