There's probably a shorter way but below works and doesn't require the starting points to be in the a column.
startindex<-3 endindex<-5.25 start<-tail(which(c$a<=startindex),1) end<-tail(which(c$a<=endindex),1) sum(c$b[start:end]) >Hello, > >A stupid question: > >I have an array with two columns, the first "a" acting as my index in 0.25 >steps, the second one "b" the column of interest. How can i sum up "b" only >for a specified window in "a" (as the window command for time series) > >a=seq(0,10,0.25) >b=runif(41) >c=data.frame(a,b) > >Sum up c if 3<a<5.25 > >How to do that? thanks > >marc >-- >Psssst! Schon vom neuen GMX MultiMessenger gehört? >Der kann`s mit allen: http://www.gmx.net/de/go/multimessenger > >______________________________________________ >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.
