Hi r-help-boun...@r-project.org napsal dne 26.08.2009 10:36:22:
> 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. One way is to use subset, order and head head(subset(your.data[order(your.data$B, decreasing=T),], subset = C<2 & A=="x"), 3) Regards Petr > > Any suggestions? > > ______________________________________________ > 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.
