Hi, Please try ?rle t.x <- x[order(x[,1],x[,2]),] t.x[cumsum(rle(t.x[,1])$lengths),] ----- A R learner. -- View this message in context: http://r.789695.n4.nabble.com/Fwd-duplicates-tp2306555p2306617.html Sent from the R help mailing list archive at Nabble.com.