strptime produces a POSIXlt result and you likely intended POSIXct instead:
as.POSIXct(x, format = "%Y/%m/%d %H:%M") for storing in a data frame. Also to avoid time zone problems down the line you might want to use chron: library(chron) as.chron(x, format = "%Y/%m/%d %H:%M") See R News 4/1. On Sun, Jul 19, 2009 at 6:26 AM, <am...@xs4all.nl> wrote: > I have timstamped data like this: > >> sd[1:10,] > Tstamp Density Mesh50 Mesh70 Mesh100 Mesh150 Mesh200 > 2 2009/02/27 07:00 30.5 0.7 10.7 21.4 32.8 41.6 > 3 2009/02/27 08:00 32.2 1.6 12.4 23.3 34.5 43.0 > 4 2009/02/27 09:00 32.7 4.8 13.0 24.0 35.1 43.5 > 5 2009/02/27 10:00 26.7 0.3 6.5 17.6 28.1 36.9 > 6 2009/02/27 11:00 26.6 0.9 6.6 17.0 28.6 37.9 > 7 2009/02/27 12:00 23.3 6.3 3.4 14.0 25.5 34.6 > 8 2009/02/27 13:00 25.2 1.1 5.1 15.4 27.3 36.8 > 9 2009/02/27 14:00 28.6 0.2 8.7 19.4 30.9 40.0 > 10 2009/02/27 15:00 28.0 0.6 8.0 18.6 30.2 39.3 > 11 2009/02/27 16:00 28.3 0.9 8.3 18.9 30.5 39.5 > > The timstamps are character vectors: > >> str(sd) > 'data.frame': 591 obs. of 7 variables: > $ Tstamp : chr "2009/02/27 07:00" "2009/02/27 08:00" "2009/02/27 09:00" > "2009/02/27 10:00" ... > $ Density: num 30.5 32.2 32.7 26.7 26.6 23.3 25.2 28.6 28 28.3 ... > $ Mesh50 : num 0.7 1.6 4.8 0.3 0.9 6.3 1.1 0.2 0.6 0.9 ... > $ Mesh70 : num 10.7 12.4 13 6.5 6.6 3.4 5.1 8.7 8 8.3 ... > $ Mesh100: num 21.4 23.3 24 17.6 17 14 15.4 19.4 18.6 18.9 ... > $ Mesh150: num 32.8 34.5 35.1 28.1 28.6 25.5 27.3 30.9 30.2 30.5 ... > $ Mesh200: num 41.6 43 43.5 36.9 37.9 34.6 36.8 40 39.3 39.5 ... > - attr(*, "na.action")=Class 'exclude' Named int [1:58] 1 88 89 90 250 > 318 319 320 321 322 ... > .. ..- attr(*, "names")= chr [1:58] "1" "88" "89" "90" ... > > Trying to transform the timestamped character vector 'in place' using > transform gives this error message: > >> sd<-transform(sd,Tstamp=strptime(Tstamp,format='%Y/%m/%d %H:%M')) > Error in `[<-.data.frame`(`*tmp*`, inx[matched], value = list(Tstamp = > list( : > replacement element 1 has 9 rows, need 591 > > Why? It beats me... > > I do have a backup of course: > > td<-strptime(sd$Tstamp,format='%Y/%m/%d %H:%M') > sd<-data.frame(Tstamp=td, sd[2:7]) > > this works fine but is one step more complicated. Something I miss about > transform()? > > Thanks in advance, > Alex van der Spek > > ______________________________________________ > 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. > ______________________________________________ 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.
