[R] Convert Character to Date

Greg Snow Greg.Snow at imail.org
Wed Apr 1 21:57:55 CEST 2009


Just to correct/expand/clarify the parenthetical below (how often is there a chance to correct or clarify something posted by Bill Venables?), the ides are the 15th of March, May, July, and October, but the 13th of the other months.  So if you want to use the ides as the date to use, you will need a vector rather than the scalar 15, if you use 15, then it will only be the ides of some months.

I wonder if the roman calendar was created on kalends April, but no one got the joke. 

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Bill.Venables at csiro.au
> Sent: Tuesday, March 31, 2009 1:29 AM
> To: quagmire54321 at yahoo.com; r-help at r-project.org
> Subject: Re: [R] Convert Character to Date
> 
> If you want the vector to be a Date you need to specify a date at least
> down to the day.  Otherwise the date is not well defined and becomes
> <NA> as you noted.
> 
> Perhaps the easiest thing is to give it a particular day of the month,
> e.g. the first, or the 15 (the "ides"), or ...
> 
> > x <- as.Date(paste("1990-January", 1, sep="-"), format = "%Y-%B-%d")
> > x
> [1] 1990-01-01
> 
> Now if you want to display the date suppressing the dummy day, you can
> 
> > y <- format(x, "%Y-%B")
> > y
> [1] "1990-January"
> 
> 
> Bill Venables
> http://www.cmis.csiro.au/bill.venables/
> 
> 
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Bob Roberts
> Sent: Tuesday, 31 March 2009 5:14 PM
> To: r-help at r-project.org
> Subject: [R] Convert Character to Date
> 
> Hello,
>    I have a date in the format Year-Month Name (e.g. 1990-January) and
> R classes it as a character. I want to convert this character into a
> date format, but when I try as.Date(1990-January, "%Y-%B"), I get back
> NA. The function strptime also gives me NA back. Thanks.
> 
> 
> 
> 
> 	[[alternative HTML version deleted]]
> 
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