In R "array" would mean a matrix, not a data frame. Also, let's name the frame "cc" as "c" is the name of a commonly used function, and so should be avoided as the name for an object. In any case, a straightforward translation using indexing seems simplest:
sum(cc[cc[,"a"] <= 5.25 & cc[,"a"] >= 3, "b"]) Why pursue complexity when the straightforward approach is transparent? Bert Gunter Genentech Nonclinical Statistics -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, November 07, 2007 9:02 AM To: [EMAIL PROTECTED] Cc: r-help@r-project.org Subject: Re: [R] partially sum variable of a dataframe 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. ______________________________________________ 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.
