Thanks. It seems that substrings only subset the data, not convert the format. For example, I use the code below: DF$time = substring(DF$time, '%Y-%m-%d')
where DF$time has the structure: '2002-01-01 00:00:00', '2002-01-01 12:00:00', '2003-01-01 00:00:00', '2003-01-01 12:00:00', etc. I wanted to convert the 'time' column to '2002-01-01', '2002-01-01', '2003-01-01', '2003-01-01', etc. Using the code above, it gives the error message: Error in as.POSIXlt.character(as.character(x), ...) : character string is not in a standard unambiguous format On Sat, Dec 31, 2016 at 10:36 AM, Bert Gunter <bgunter.4...@gmail.com> wrote: > ?substring > > (among others) > > -- Bert > Bert Gunter > > "The trouble with having an open mind is that people keep coming along > and sticking things into it." > -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) > > > On Sat, Dec 31, 2016 at 9:26 AM, lily li <chocol...@gmail.com> wrote: > > Hi all, > > > > Thanks for your help. Now I can convert data to the format "yyyy-mm-dd > > hh:mm:ss", but how to convert it to "yyyy-mm-dd"? The datasets are txt > > files, not from excel. > > > > On Fri, Dec 30, 2016 at 3:01 PM, Duncan Mackay <dulca...@bigpond.com> > wrote: > > > >> Hi > >> > >> Is this the output from Excel? > >> If so format it in Excel for a date format not a date-time format . > >> Depending how the dates were inputted into Excel and the Excel setup a > date > >> may not be a date format. > >> There are no rules with microsoft formatting so beware! > >> > >> > >> Regards > >> > >> Duncan > >> > >> Duncan Mackay > >> Department of Agronomy and Soil Science > >> University of New England > >> Armidale NSW 2351 > >> Email: home: mac...@northnet.com.au > >> > >> -----Original Message----- > >> From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of lily li > >> Sent: Saturday, 31 December 2016 05:38 > >> To: Rui Barradas > >> Cc: R mailing list > >> Subject: Re: [R] about data format in R > >> > >> Hi Rui, > >> > >> Thanks for your reply. When I read in data using my code, the first > column > >> ranges from 0 to 1. So when I use the code you wrote, it shows the error > >> message: > >> Error in as.POSIXct.numeric(DF$Date, format = "%m/%d/%Y-%H:%M:%S") : > >> 'origin' must be supplied > >> > >> > >> On Fri, Dec 30, 2016 at 11:23 AM, Rui Barradas <ruipbarra...@sapo.pt> > >> wrote: > >> > >> > Hello, > >> > > >> > Have you tried > >> > > >> > df$date <- as.POSIXct(dat$date, format = "%m/%d/%Y-%H:%M:%S") > >> > > >> > ? > >> > > >> > Hope this helps, > >> > > >> > Rui Barradas > >> > > >> > > >> > > >> > Em 30-12-2016 17:40, lily li escreveu: > >> > > >> >> Hi R users, > >> >> > >> >> I'm trying to read in data, and then plot time series data. However, > I > >> >> have > >> >> some problems. In my dataset, the first column represents time, and > in > >> the > >> >> format: > >> >> mm/dd/yyyy-hr:min:sec; For example, 10/01/1995-00:00:00, > >> >> 10/01/1995-06:00:00, etc. > >> >> > >> >> df: > >> >> date evap precip intercept > >> >> 10/01/1995-00:00:00 1.5 2 0.2 > >> >> 10/01/1995-12:00:00 1.7 2.2 0.1 > >> >> 10/02/1995-00:00:00 1.5 1.8 0.3 > >> >> ... > >> >> > >> >> My code is like this > >> >> file1 = read.table('df', head=T) > >> >> > >> >> When I read in data, I found that it read incorrectly. How to format > >> when > >> >> read in data? Thanks. > >> >> > >> >> [[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/posti > >> >> ng-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. > >> > >> ______________________________________________ > >> 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. > [[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.