Thanks David and Duncan, Before I posted I was considering the approach of multiplying week by 7, but I couldn't see a clean way to do it so it'll work for any year, and get Monday's date correct. I now realize I could write code to evaluate which of the first 7 days in the year is a Monday and then I'd know the start of week 1 in each year, and multiply from there. Thanks Michael
-----Original Message----- From: David Winsemius [mailto:dwinsem...@comcast.net] Sent: August 17, 2011 2:38 PM To: Folkes, Michael Cc: r-help@r-project.org Subject: Re: [R] Convert week value to date On Aug 17, 2011, at 4:52 PM, Folkes, Michael wrote: > Hello all, > I'm hoping to convert a decimal value for week of the year back to a > date object. > Eg: > strptime(paste(2010,1:52,sep=" "),format="%Y %W") Yeah, agree that seems as though it should have been successful. I cannot get any of my invocations using %W to work. > strptime(Sys.Date(), "%Y-%m-%d-%W") [1] NA > strptime(Sys.Date(), "%Y-%m-%d") [1] "2011-08-17" > strptime(Sys.Date(), "%Y-%m-%d %W") [1] NA Oh well. seq.POSIXt(as.POSIXlt("2010-01-01"), by="week", length=52) > > I expected (hoped?) this would give me the date for Monday of each > week. Instead, it's giving me 52 values of today's date. > > Where am I erring? > Thanks > Michael > David Winsemius, MD West Hartford, CT ______________________________________________ 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.
