That is wonderful. Thank you. Adele
Ken Takagi wrote: > > Schatzi <adele_thompson <at> cargill.com> writes: > >> >> I have a combined date and time. I would like to separate them out into >> two >> columns so I can do things such as take the mean by time across all >> dates. >> >> meas<-runif(435) >> nTime<-seq(1303975800, 1304757000, 1800) >> nDateT<-as.POSIXct(nTime, origin="1970-01-01") >> mat1<-cbind(nDateT,meas) >> >> means1<- aggregate(mat1$meas, list(nDateT), mean) >> >> This doesn't do anything as each day is different, but if I had just the >> time, it would take the mean outputing 48 values (for each 30 min). >> >> Also, sometimes there are missing meas to a specific time. Is there >> anyway >> to copy the previous meas if one is missing? >> >> ----- >> In theory, practice and theory are the same. In practice, they are not - > Albert Einstein >> -- >> View this message in context: > http://r.789695.n4.nabble.com/separate-date-and-time-tp3517571p3517571.html >> Sent from the R help mailing list archive at Nabble.com. >> >> > > Not sure if this is what you want, but you can use substr to split nDateT > into > date and time, and then use aggregate() in the time column in df1. > > meas<-runif(435) > nTime<-seq(1303975800, 1304757000, 1800) > nDateT<-as.POSIXct(nTime, origin="1970-01-01") > date <- substr(nDateT, 1, 10) > time <- substr(nDateT, 12, 19) > df1 <- data.frame(date, time, meas) > > means1<- aggregate(df1$meas, list(df1$time), mean) > > HTH, > Ken > > ______________________________________________ > 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. > ----- In theory, practice and theory are the same. In practice, they are not - Albert Einstein -- View this message in context: http://r.789695.n4.nabble.com/separate-date-and-time-tp3517571p3517999.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.
