Hi all, the moment you hit the 'send' button you know the answer...
I approached a solution similar to this one given by Marc. But maybe there is a better one? Even because this operation is done in a for-loop during which R gets new data from a database. So I sum up 16 data.frames eventually. Dubro -----Ursprüngliche Nachricht----- Von: Marc Schwartz [mailto:[EMAIL PROTECTED] Gesendet: Dienstag, 6. Dezember 2005 15:11 An: Dubravko Dolic Cc: r-help@stat.math.ethz.ch Betreff: Re: [R] merging with aggregating On Tue, 2005-12-06 at 14:22 +0100, Dubravko Dolic wrote: > Dear List, > > I have two data.frame of the following form: > > A: > > n V1 V2 > 1 12 0 > 2 10 8 > 3 3 8 > 4 8 4 > 6 7 3 > 7 12 0 > 8 1 0 > 9 18 0 > 10 1 0 > 13 2 0 > > B: > > n V1 V2 > 1 0 2 > 2 0 3 > 3 1 9 > 4 12 8 > 5 2 9 > 6 2 9 > 8 2 0 > 10 4 1 > 11 7 1 > 12 0 1 > > > Now I want to merge those frame to one data.frame with summing up the > columns V1 and V2 but not the column n. So the result in this example > would be: > > AB: > > n V1 V2 > 1 12 2 > 2 10 11 > 3 4 17 > 4 20 12 > 5 2 9 > 6 9 12 > 7 12 0 > 8 3 0 > 9 18 0 > 10 5 1 > 11 7 1 > 12 0 1 > 13 2 0 > > > So Columns V1 and V2 are the sum of A und B while n has its old value. > Notice that there are different rows in n of A and B. > > I don't have a clue how to start here. Any hint is welcome. > > Thanks There might be a somewhat easier way, but here is one approach: # Use merge() to join A and B on 'n' # Set all = TRUE to include non-matched rows > C <- merge(A, B, by = "n", all = TRUE) > C n V1.x V2.x V1.y V2.y 1 1 12 0 0 2 2 2 10 8 0 3 3 3 3 8 1 9 4 4 8 4 12 8 5 5 NA NA 2 9 6 6 7 3 2 9 7 7 12 0 NA NA 8 8 1 0 2 0 9 9 18 0 NA NA 10 10 1 0 4 1 11 11 NA NA 7 1 12 12 NA NA 0 1 13 13 2 0 NA NA # Now get the rowSums() for the V1/V2 column pairs # and create a new dataframe from the # results > AB <- data.frame(n = C$n, V1 = rowSums(C[, c(2, 4)], na.rm = TRUE), V2 = rowSums(C[, c(3, 5)], na.rm = TRUE)) > AB n V1 V2 1 1 12 2 2 2 10 11 3 3 4 17 4 4 20 12 5 5 2 9 6 6 9 12 7 7 12 0 8 8 3 0 9 9 18 0 10 10 5 1 11 11 7 1 12 12 0 1 13 13 2 0 See ?merge and ?rowSums for more information. HTH, Marc Schwartz ______________________________________________ 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