Jessica Any good? lines <-"DateTime, Q 2004-12-09 15:30:01, 2 2004-12-09 15:30:01, 1 2004-12-09 15:30:06, 1 2004-12-09 15:30:14, 5 2004-12-09 15:30:21, 1 2004-12-09 15:30:22, 11 2004-12-09 15:30:24, 4 2004-12-09 15:30:32, 1 2004-12-09 15:30:32, 1 2004-12-09 15:30:32, 3 2004-12-09 15:30:41, 4" d = read.table(textConnection(lines), sep="," ,header = TRUE) d$DateTime = as.POSIXct(d$DateTime) time <- seq(as.POSIXct('2004-12-09 15:30:00'),by='5 sec', length=10) bins = cut(d$DateTime,breaks=time) counts = as.data.frame(tapply(d$Q,bins,sum)) # Clean up counts[is.na(counts)]=0 colnames(counts) = "Counts" print(counts) HTH Pete -- View this message in context: http://r.789695.n4.nabble.com/time-bin-sum-tp3252376p3253400.html Sent from the R help mailing list archive at Nabble.com.