Try this: DF <- read.csv(textConnection("V1,V2,V3 10:03:13,3.4,1002 10:03:14,5.6,1001 10:05:27,7.2,999 10:05:33,8.2,998"), header = TRUE)
tDates <- strptime(DF$V1, "%H:%M:%S") tDates[[2]] <- floor(strptime(DF$V1, "%H:%M:%S")[[2]] / 5) * 5 aggregate(DF[,c('V2', 'V3')], list(format(tDates, "%H:%M:00")), FUN = sum) On Thu, Mar 11, 2010 at 6:48 AM, ManInMoon <xmoon2...@googlemail.com> wrote: > > I have a matrix with a POSIXct as a numeric in the first column. > > I would like to create a new matrix that is "grouped by" my chosed time > bars. > > i.e. So I would like to group by hour or day or 5 days, and have all my > columns be summed or averaged or counted.. > > mydata: > > V1,V2,V3 > 10:03:13,3.4,1002 > 10:03:14,5.6,1001 > 10:05:27,7.2,999 > 10:05:33,8.2,998 > > I want to convert this into say 5 minutes "bars" and sum columns > > mynewdata: > > V1,V2,V3 > 10:00:00,9.0,2003 > 10:05:00,15.4,1997 > > > How can I do this? > -- > View this message in context: > http://n4.nabble.com/Group-by-tp1588694p1588694.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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O ______________________________________________ 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.