Try this: fa$sum <- ave(fa$X1, fa$X3, FUN = sum)
On 2/8/07, sun <[EMAIL PROTECTED]> wrote: > Hi, > > Maybe this is a trivial question but I can not figure out a good solution. > > I have a data frame fa and want to add a new column "sum" with the sum value > of fa$X1 grouped by fa$X3. > > > fa > X1 X2 X3 > 1 1 11 1 > 2 2 12 1 > 3 3 13 1 > 4 4 14 2 > 5 5 15 2 > 6 6 16 2 > 7 7 17 3 > 8 8 18 3 > 9 9 19 3 > 10 10 20 3 > > fa$X3 is the index of group > > i can > > >aggregate(fa[,"X1"],list(fa$X3),sum) > Group.1 x > 1 1 6 > 2 2 15 > 3 3 34 > > then I want to add a new column "sum" in fa and assign the aggregated result > to the new column. Is there a solution without using loops? > or maybe there is some way can even avoid aggregate operation? > > Thanks. > > ______________________________________________ > R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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.
