test <- data.frame(ID=c(1,1,1,2,2,2),data=1:6)
do.call("rbind", by(test,test$ID,function(x)x[2,]) )--- On Thu 10/09, Jean Eid < [EMAIL PROTECTED] > wrote: From: Jean Eid [mailto: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Date: Thu, 9 Oct 2003 16:06:12 -0400 Subject: [R] subsetting objects I want to be able to exctract a matrix from a data frame that contains repeated measurements for individuals. i.e I want to exctract the second observation for each individual in the study. <br>Is there a way of doing this? <br><br>I guess what I am trying to ask is if there as a multidimensional version of aggregate() as in aggregate(data, list(data[,"ID"]), function(x) x[2,])<br>but aggregate will only give back scalars. <br><br>Thank you, <br>Jean<br> [[alternative HTML version deleted]]<br><br>______________________________________________<br>[EMAIL PROTECTED] mailing list<br>https://www.stat.math.ethz.ch/mailman/listinfo/r-help<br> _______________________________________________ No banners. No pop-ups. No kidding. Introducing My Way - http://www.myway.com ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
