One way is: ac_name_count <- ave(integer(nrow(data)), data[["ac_name"]], FUN=length) data[ac_name_count <= 5, ,drop=FALSE] # rows whose ac_name entry is rare data[ac_name_count > 5, ,drop=FALSE] # rows whose ac_name entry is common Use ac_name_seqno <- ave(integer(nrow(data)), data[["ac_name"]], FUN=seq_along) to assign a within-group sequence number so you can pick out the first or last n items in a group for the big groups.
Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf > Of fxen3k > Sent: Wednesday, October 17, 2012 5:45 AM > To: r-help@r-project.org > Subject: [R] How to count rows with a condition > > Hi, > > I have a dataset called "data". There is one row called "ac_name". Some > names in this column appear very often, some less. > What I want is to filter this dataset with the following condition: > > Exclude the names, which appear more than five times. (example: House A > appears 8 times ==> exclude it; House B appears 5 times ==> include it etc.) > > In the end, I want to have the old "data" dataset excluding the rows with > the above mentioned condition and another list with all the names which have > been excluded. > > > I think for one of the professionals amongst you this is pretty easy to > solve. ;-) > > Thanks dudes! > > Cheerio, > Felix > > > > -- > View this message in context: > http://r.789695.n4.nabble.com/How-to-count-rows-with- > a-condition-tp4646454.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.
