Try this (and note that times must be less than 24 hours): > Lines <- "LogData date time + 1 77.16 2008/04/24 02:00 + 2 61.78 2008/04/24 04:00 + 3 75.44 2008/04/24 06:00 + 4 89.43 2008/04/24 08:00 + 5 95.83 2008/04/24 10:00 + 6 96.88 2008/04/24 24:00" > > DF <- read.table(textConnection(Lines)) > > library(chron) > DF2 <- transform(DF, + chron = as.chron(paste(date, time)), + POSIXct = as.POSIXct(paste(date, time))) > DF2 LogData date time chron POSIXct 1 77.16 2008/04/24 02:00 (04/24/08 02:00:00) 2008-04-24 02:00:00 2 61.78 2008/04/24 04:00 (04/24/08 04:00:00) 2008-04-24 04:00:00 3 75.44 2008/04/24 06:00 (04/24/08 06:00:00) 2008-04-24 06:00:00 4 89.43 2008/04/24 08:00 (04/24/08 08:00:00) 2008-04-24 08:00:00 5 95.83 2008/04/24 10:00 (04/24/08 10:00:00) 2008-04-24 10:00:00 6 96.88 2008/04/24 24:00 (NA NA) <NA>
On Tue, Feb 16, 2010 at 5:47 AM, Alex Anderson <complicad...@yahoo.com.au> wrote: > Hi All, > I am attempting to work with some data from loggers. I have read in a .csv > exported from MS Access that already has my dates and times (in 24 clock > format), (with StringsAsFactors=FALSE). > >> head(tdata) > > LogData date time > 1 77.16 2008/04/24 02:00 > 2 61.78 2008/04/24 04:00 > 3 75.44 2008/04/24 06:00 > 4 89.43 2008/04/24 08:00 > 5 95.83 2008/04/24 10:00 > 6 96.88 2008/04/24 24:00 > > I wish to be able to summarise the data using the character vectors $data > and $time (daily, monthly averages, maxima of my $LogData for example) so I > am trying to get R to recognise the $date and $time columns as valid dates > and times. Using... > >> tdata$date2 = as.Date(as.character(tdata$date)) > > I can get a new column of valid dates, but neither: > >> tdata$time2= strptime(tdata$time,"%k") > > Error in `$<-.data.frame`(`*tmp*`, "time2", value = list(sec = c(0, 0, : > replacement has 9 rows, data has 10 > > nor trying: > >> tdata$time2=chron(times=as.character(tdata$time, format= "hh:mm")) > > In addition: Warning messages: > 1: In unpaste(times, sep = fmt$sep, fnames = fmt$periods, nfields = 3) : > wrong number of fields in entry(ies) 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 > 2: In convert.times(times., fmt) : NAs introduced by coercion > 3: In convert.times(times., fmt) : NAs introduced by coercion > 4: In convert.times(times., fmt) : NAs introduced by coercion > > gives me any valid times from my time vector. the Chron documentation > doesn't mention 24 clocks, strptime neither, and the Rnews issue 1/4 with an > article about time is no help... Any thoughts would be much appreciated. > regards > > Alex Anderson > James Cook University > Townsville, Australia > > ______________________________________________ > 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.