On Wed, Jun 16, 2010 at 4:55 PM, Gabor Grothendieck <ggrothendi...@gmail.com> wrote: > On Wed, Jun 16, 2010 at 1:10 PM, skan <juanp...@gmail.com> wrote: >> >> I said taking the first element everyday, but that was just an example, I >> could need one every 2 hours or something more complicated such as one every >> hour if the former one was non null. > > Lines <- "1990-01-01 10:00:00 , 0.900 # element 1 > 1990-01-01 10:01:00 , 0.910 # element 2 > 1990-01-01 10:03:00 , 0.905 # element 3 > 1990-01-01 10:04:00 , 0.905 # element 4 > 1990-01-01 10:05:00 , 0.890 # element 5 > 2000-12-30 20:00:00 , 11.233 # element 3323232" > > library(zoo) > z <- read.zoo(textConnection(Lines), sep = ",", tz = "") > > # take mean of every 2 hour segment > aggregate(z, as.POSIXct(cut(time(z), "2 hours", include = TRUE)), mean) > > For more examples, see: > ?aggregate.zoo >
And here it is using chron: Lines <- "1990-01-01 10:00:00 , 0.900 # element 1 1990-01-01 10:01:00 , 0.910 # element 2 1990-01-01 10:03:00 , 0.905 # element 3 1990-01-01 10:04:00 , 0.905 # element 4 1990-01-01 10:05:00 , 0.890 # element 5 2000-12-30 20:00:00 , 11.233 # element 3323232" library(zoo) library(chron) z <- read.zoo(textConnection(Lines), sep = ",", FUN = as.chron) # take mean of every 2 hour segment aggregate(z, trunc(time(z), "02:00:00"), mean) ______________________________________________ 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.
