Hi, This should work - head is quite a usefull summary function
head(df.mydata[df.mydata$A=="X" & df.mydata$C < 2, ],3) Colin. -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Noah Silverman Sent: 26 August 2009 10:54 To: ottorino-luca.pant...@unifi.it Cc: r help Subject: Re: [R] Select top three values from data frame I only have a few values in my example, but the real data set might have 20-100 rows with A="X". So how do I pick just the three highest ones? -N On 8/26/09 2:46 AM, Ottorino-Luca Pantani wrote: > df.mydata[df.mydata$A=="X" AND df.mydata$C < 2, ] > will do the job ? > > 8rino > > Noah Silverman ha scritto: >> Hi, >> >> I'm trying to find an easy way to do this. >> >> I want to select the top three values of a specific column in a >> subset of rows in a data.frame. I'll demonstrate. >> >> A B C >> x 2 1 >> x 4 1 >> x 3 2 >> y 1 5 >> y 2 6 >> y 3 8 >> >> >> I want the top 3 values of B from the data.frame where A=X and C <2 >> >> I could extract all the rows where C<2, then sort by B, then take the >> first 3. But that seems like the wrong way around, and it also will >> get messy with real data of over 100 columns. >> >> Any suggestions? >> [[alternative HTML version deleted]] ______________________________________________ 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. ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________ 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.
