My point is this: if we do
temp<-tDates aggregate(DF[,c('V2', 'V3')], list(format(temp, "%H:%M:00")), FUN = sum) Does agrregate still know it's refering to DF$V1 - and if so- how? -- View this message in context: http://n4.nabble.com/Group-by-tp1588694p1589600.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.