aggregate(c$a, list(b=b), sum) --- marcg <[EMAIL PROTECTED]> wrote:
> Hello R > > For expierienced user, the following problem will be > easy to solve: > > a<-c(0,1,0,1,0,2,3,4,3,2) > b<-c(3,3,3,4,4,4,7,7,7,10) > c<-data.frame(a,b) > > Data Frame c contains tow colums. I would like to > sum up all values in a as long as b stays the same: > > sum(a[which(b==1)]) > > does this, but i have to manually put in b > > then i tryied st like this, but i canno't save it > properly > > for (i in 0:max(b)){ > i<-sum(a[which(b==i)]) > } > > i tried to figure out, how tapply works, but neither > > thanks alot > > marc > -- > > ______________________________________________ > 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.