I don't know what you really want, but reshape will help you. reshape(mydata, timevar="taskid",idvar="userid", direction="wide") ----- A R learner. -- View this message in context: http://r.789695.n4.nabble.com/split-lapply-over-multiple-columns-tp2312871p2312909.html Sent from the R help mailing list archive at Nabble.com.