This isn't really a bug so much as an undocumented feature, but perhaps the help file should be changed. If you say match(x,y) you get the values of the _first_ instance in y that matches each value of x. If you say x %in% y you get "TRUE" for every match, not just the first. This is useful, now that I know it, but perhaps the thing about the first instance should be documented. I still don't understand why it happens! Jon -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
match vs. %in% (PR#853)
2 messages · Jonathan Baron, Brian Ripley
On Sun, 18 Feb 2001 baron@cattell.psych.upenn.edu wrote:
This isn't really a bug so much as an undocumented feature, but perhaps the help file should be changed. If you say match(x,y) 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, ripley@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 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-devel mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-devel-request@stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._