Hi, I am not sure about the logic behind creation of groups, especially, how do you want to assign the group number to a particular combination of Feature and OS. One possible way would be: dat1$Group<-paste(dat1[,1],dat1[,2],sep="") > dat1 # Feature OS Group #1 4 2 42 #2 4 1 41 #3 4 3 43 #4 1 2 12 #5 4 1 41 A.K.
----- Original Message ----- From: Tammy Ma <metal_lical...@live.com> To: "r-help@r-project.org" <r-help@r-project.org> Cc: Sent: Tuesday, January 22, 2013 4:28 AM Subject: [R] How to align group based on the common values of two columns in r HI, I met this problem: I have the feature data frame: Feature OS 4 2 4 1 4 3 1 2 4 1 what I want to do is to autimatically create one more column called "group": Feature OS Group 4 2 1 4 1 2 4 3 3 1 2 4 4 1 2 I don't want "Ifelse", because I have so many combination of feature and OS, I even can not account. I just want to have sth to autimatically create group indicator based on the difference combination of feature and OS. Thanks for your help. Kind regards, Tammy [[alternative HTML version deleted]] ______________________________________________ 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.