Try this also: times <- as.POSIXlt(mytime, format = "%H:%M:%S") subTimes <- times[times[['min']] %in% c(0,15,30,45)] format(subTimes[!duplicated(format(subTimes, "%H:%M"))], "%H:%M:%S")
On Thu, Aug 13, 2009 at 5:10 PM, Tim Clark <mudiver1...@yahoo.com> wrote: > Dear List, > > I have a data frame of data taken every few seconds. I would like to > subset the data to retain only the data taken on the quarter hour, and as > close to the quarter hour as possible. So far I have figured out how to > subset the data to the quarter hour, but not how to keep only the minimum > time for each quarter hour. > > For example: > > mytime<-c("12:00:00","12:00:05","12:15:05","12:15:06","12:20:00","12:30:01","12:45:01","13:00:00","13:15:02") > > subtime<-grep(pattern="[[:digit:]]+[[:punct:]]00[[:punct:]][[:digit:]]+|[[:digit:]]+[[:punct:]]15[[:punct:]][[:digit:]]+|[[:digit:]]+[[:punct:]]30[[:punct:]][[:digit:]]+|[[:digit:]]+[[:punct:]]45[[:punct:]][[:digit:]]+",mytime) > mytime[subtime] > > [1] "12:00:00" "12:00:05" "12:15:05" "12:15:06" "12:30:01" "12:45:01" > "13:00:00" "13:15:02" > > This gives me the data taken at quarter hour intervals (removes 12:20:00) > but I am still left with multiple values at the quarter hours. > > I would like to obtain: > > "12:00:00" "12:15:05" "12:30:01" "12:45:01" "13:00:00" "13:15:02" > > Thanks! > > Tim > > > > > Tim Clark > Department of Zoology > University of Hawaii > > ______________________________________________ > 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 [[alternative HTML version deleted]]
______________________________________________ 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.