see also tapply() e.g.
a<-c(1,1,1,2,2,2,3,3,3) b<-c(10,10,10,15,15,15,20,20,20) c.dat<-data.frame(a,b) tapply(c.dat[,2],c.dat[,1],sum) Mike On Thu, Dec 2, 2010 at 10:33 AM, Ivan Calandra <ivan.calan...@uni-hamburg.de > wrote: > see ?aggregate, and ?summaryBy (in package doBy) > I think ddply (in package plyr) could also do the job > > Ivan > > Le 12/2/2010 17:24, chris99 a écrit : > >> I am trying to aggregate data in column 2 to identifiers in col 1 >> >> eg.. >> >> take this> >> >> identifier quantity >> 1 10 >> 1 20 >> 2 30 >> 1 15 >> 2 10 >> 3 20 >> >> and make this> >> >> identifier quantity >> 1 45 >> 2 40 >> 3 20 >> >> >> Thanks in advance for your help! >> > > -- > Ivan CALANDRA > PhD Student > University of Hamburg > Biozentrum Grindel und Zoologisches Museum > Abt. Säugetiere > Martin-Luther-King-Platz 3 > D-20146 Hamburg, GERMANY > +49(0)40 42838 6231 > ivan.calan...@uni-hamburg.de > > ********** > http://www.for771.uni-bonn.de > http://webapp5.rrz.uni-hamburg.de/mammals/eng/1525_8_1.php > > ______________________________________________ > 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<http://www.r-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code. > -- Michael Rennie, Research Scientist Fisheries and Oceans Canada, Freshwater Institute Winnipeg, Manitoba, CANADA [[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.
