Is this what you want to do? D2 <- expand.grid(Class=unique(D$Class), X=unique(D$X)) D2 <- merge(D2, D, all=TRUE) D2$Count[is.na(D2$Count)] <- 0
W <- aggregate(D2$Count, list(D2$Class, D2$X), "sum") W Best, Nello -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of IOANNA Sent: Freitag, 15. März 2013 13:41 To: r-help@r-project.org Subject: [R] Data manipulation Hello all, I would appreciate your thoughts on a seemingly simple problem. I have a database, where each row represent a single record. I want to aggregate this database so I use the aggregate command : D<-read.csv("C:\\Users\\test.csv") attach(D) by1<-factor(Class) by2<-factor(X) W<-aggregate(x=Count,by=list(by1,by2),FUN="sum") The results I get following the form: >W Group.1 Group.2 x 1 1 0.1 4 2 2 0.1 7 3 3 0.1 1 4 1 0.2 3 5 3 0.2 4 6 3 0.3 4 However, what I really want is an aggregation which includes the zero values, i.e.: >W Group.1 Group.2 x 1 1 0.1 4 2 2 0.1 7 3 3 0.1 1 4 1 0.2 3 2 0.2 0 5 3 0.2 4 1 0.3 0 2 0.3 0 6 3 0.3 4 How can I achieve what I want? Best regards, Ioanna ______________________________________________ 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.
