Building on Don's example here is something that looks a lot like what I do every day: Sys.setenv(TZ="UTC") mydf <- data.frame(t1=c('2011-12-31-22-30', '2011-12-31-23-30')) library(lubridate) mydf$timestamp = lubridate::ymd_hm(mydf$t1) mydf$t2 = mydf$timestamp - period(minute=30)
On Wed, Aug 31, 2016 at 2:44 PM, MacQueen, Don <macque...@llnl.gov> wrote: > Try following this example: > > mydf <- data.frame(t1=c('201112312230', '201112312330')) > tmp1 <- as.POSIXct(mydf$t1, format='%Y%m%d%H%M') > tmp2 <- tmp1 - 30*60 > mydf$t2 <- format(tmp2, '%Y%m%d%H%M') > > It can be made into a single line, but I used intermediate variables tmp1 > and tmp2 so that it would be easier to follow. > > Base R is more than adequate for this task. > > Please get rid of the asterisks in your next email. The just get in the > way. Learn how to send plain text email, not HTML email. Please. > > > > > -- > Don MacQueen > > Lawrence Livermore National Laboratory > 7000 East Ave., L-627 > Livermore, CA 94550 > 925-423-1062 > > > > > > On 8/31/16, 9:07 AM, "R-help on behalf of Bhaskar Mitra" > <r-help-boun...@r-project.org on behalf of bhaskar.kolk...@gmail.com> > wrote: > > >Hello Everyone, > > > >I am trying a shift the time series in a dataframe (df) by 30 minutes . My > >current format looks something like this : > > > > > > > >*df$$Time 1* > > > > > >*201112312230* > > > >*201112312300* > > > >*201112312330* > > > > > > > >*I am trying to add an additional column of time (df$Time 2) next to Time > >1 by lagging it by 30minutes. Something like this :* > > > > > >*df$Time1 **df$$Time2* > > > > > >*201112312230 **201112312200* > > > >*201112312300 **201112312230* > > > >*201112312330 **201112312300* > > > >*201112312330 * > > > > > > > > > > > >*Based on some of the suggestions available, I have tried this option * > > > > > > > >*require(zoo)* > > > >*df1$Time2 <- lag(df1$Time1, -1, na.pad = TRUE)* > > > >*View(df1)* > > > > > > > >*This does not however give me the desired result. I would appreciate any > >suggestions/advice in this regard.* > > > > > >*Thanks,* > > > >*Bhaskar* > > > > [[alternative HTML version deleted]] > > > >______________________________________________ > >R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > >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 -- To UNSUBSCRIBE and more, see > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.