I said taking the first element everyday, but that was just an example, I could need one every 2 hours or something more complicated such as one every hour if the former one was non null. -- View this message in context: http://r.789695.n4.nabble.com/working-with-zoo-time-index-tp2255804p2257641.html Sent from the R help mailing list archive at Nabble.com.