Wow! A bold prediction from someone who has done exactly zero investigation of the basic, built-in date/time features in R. Since your example did not include the first two digits of the year, I've used %y instead of %Y. That will assume "19" precedes values from 69-99 and "20" precedes values from 00 to 68. If you decide to implement this with a for loop, it means you have much more to learn.
> today <- "3/4/15" > d1 <- "2/15/80" > d2 <- "2/15/16" > # Is d before today, if so 0, otherwise 1 > as.integer(strptime(today, "%m/%d/%y") < strptime(d1, "%m/%d/%y")) [1] 0 > as.integer(strptime(today, "%m/%d/%y") < strptime(d2, "%m/%d/%y")) [1] 1 ?strptime for details ------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Brian Hamel Sent: Wednesday, March 4, 2015 8:55 AM To: r-help@r-project.org Subject: [R] Using dates in R Hi all, I have a dataset that includes a "date" variable. Each observation includes a date in the form of 2/15/15, for example. I'm looking to create a new indicator variable that is based on the date variable. So, for example, if the date is earlier than today, I would need a "0" in the new column, and a "1" otherwise. Note that my dataset includes dates from 1979-2012, so it is not one-year (this means I can't easily create a new variable 1-365). How does R handle dates? My hunch is "not well," but perhaps there is a package that can help me with this. Let me know if you have any recommendations as to how this can be done relatively easily. Thanks! Appreciate it. Best, Brian [[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.
