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.
Is there a way of doing this?
I guess what I am trying to ask is if there as a multidimensional version
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
