[R] Using dates in R

[Myfanwy Johnston]

Our R-user's group (UC Davis) has a good post on working with dates/times
in R:
http://www.noamross.net/blog/2014/2/10/using-times-and-dates-in-r---presentation-code.html



On Wed, Mar 4, 2015 at 11:08 AM, David L Carlson <dcarlson at tamu.edu> wrote:

> 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-bounces at r-project.org] On Behalf Of Brian
> Hamel
> Sent: Wednesday, March 4, 2015 8:55 AM
> To: r-help at 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 at 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 at 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.
>



-- 
Myfanwy Johnston
Ph.D Candidate, Animal Behavior
University of California at Davis
Biotelemetry Lab
+1.530.205.5243

	[[alternative HTML version deleted]]