Hi, I am sure there are better / more efficient ways of doing this, but the following seems to work ...
ids <- sapply(split(df,df$ID),function(x) {length(x$rel.head)==2 & any(x$rel.head==1) & any(x$rel.head==3)}) ids <- as.numeric(names(ids)[ids]) added.dummy <- as.numeric(df$ID%in%ids) cbind(df,added.dummy) Martyn -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of gra...@stat.columbia.edu Sent: 04 October 2011 16:45 To: r-help@r-project.org Subject: [R] adding a dummy variable... Hi all, I have a dataset of individuals where the variable ID corresponds to the identification of the household where the individual lives. rel.head stands for the relationship with the household head. so rel.head=1 is the household head, rel.head=2 is the spouse, rel.head=3 is the children. Here is an example to see how it looks like: df<-data.frame(ID=c("17100", "17100", "17101", "17102", "17103", "17103", "17104", "17104", "17104", "17105", "17105"), rel.head=c("1","3","1","1","1", "2", "1", "2", "3", "1", "3")) I want to add a dummy variable that is equal to 1 when these conditions held simultaneously : a) the number of rows with same ID is equal to 2 b) the variable rel.head=1 and rel.head=3 So my ideal output is: ID rel.head added.dummy 1 17100 1 1 2 17100 3 1 3 17101 1 0 4 17102 1 0 5 17103 1 0 6 17103 2 0 7 17104 1 0 8 17104 2 0 9 17104 3 0 10 17105 1 1 11 17105 3 1 Is there a simple way to do that? Can somebody help? Thanks in advance, Grazia ______________________________________________ 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. ________________________________________________________________________ This e-mail has been scanned for all viruses by Star.\ _...{{dropped:12}} ______________________________________________ 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.