[R] Week value function

[David Winsemius]

I am not seeing anything but that proves nothing of course. You could  
write your own function and stick it in the .First of your .Rprofile  
files that get loads at startup.

Details here:
http://cran.r-project.org/doc/contrib/Lemon-kickstart/kr_first.html

week.dBY <- function(x) format(strptime(x, "%d%B%Y") ,  "%W")

 > dt<-"07JAN2009"
 > week.dBY(dt)
[1] "01"  # a character valued vector

Gives "00" for "01JAN2009" but you can adjust that behavior to your  
specifications. You could also convert to numeric if desired:

 > nweek.dBY <- function(x) as.integer(format(strptime(x, "%d%B%Y") ,   
"%W"))
 > nweek.dBY(dt)
[1] 1

-- 
David Winsemius

On Mar 7, 2009, at 12:34 PM, Pele wrote:

>
> Hi R users,
>
> I am looking for a date function that will give the following:
> 	- The number-of-week value is in the range 01-53
> 	- Weeks begin on a Monday and week 1 of the year is the week that
> 	  includes both January 4th and the first Thursday of the year.
>          If the first Monday of January is the 2nd, 3rd, or 4th, the 	
> preceding days are part
>         of the last week of the preceding year.  This is similar to  
> the
> SAS's week function with option V.
>
> I am currently using :
>
> 	date <- strptime(DATE, "%d%B%Y")
> 	week <- format(date, "%W")
>
> but, I could not find an option for doing the above description
> automatically.  Can anyone help?
>
> Thanks in advance for any help.
>
> -- 
> View this message in context: http://www.nabble.com/Week-value-function-tp22389878p22389878.html
> Sent from the R help mailing list archive at Nabble.com.
>
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT