I'd use a combination of rownames(), grepl() and sum(). Get the names with the first, test with the second and count the positives (by coercing TRUE -> 1) with the last
Michael On Apr 29, 2012, at 3:46 PM, katarv <katiasm...@gmail.com> wrote: > Hi, > > I have a large data set that I input as a matrix, where I have 1:x rows > with names AX, then x+1: y rows named AY, etc. The idea is that I have to > count how many rows exactly I have with name AX and how many I have with > name AY (or find which row numbers have names AX). Is there any way in R to > count a number of rows with a name matching a required pattern? > > > Thanks in advance, > > Katie > > -- > View this message in context: > http://r.789695.n4.nabble.com/Count-number-of-rows-in-a-matrix-with-a-character-pattern-tp4596848p4596848.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@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@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.
