R help - Aug 2011 - having trouble extracting week from chron object

Running R 2.13.1 on Windows XP.
I would like to get week of the year (1-52) for each date.

library(chron)
dts <- dates(c("02/27/92", "02/27/92",
"01/14/92","02/28/92", "02/01/92"))
dts
dts.chron <- as.chron(dts)
dts.chron
class(dts.chron)
# all of these component extractions work:
months(dts.chron)
weekdays(dts.chron)
years(dts.chron)
quarters(dts.chron)
# but weeks() doesn't seem to work
weeks(dts.chron)

?chron tells me: . . . The functions days(), months(), quarters(),
years(), weeks(), weekdays(), hours(), minutes(), and seconds() take
any chron object as input and extract the corresponding time interval
. . . .

Any advice?

Thanks.

Chris Ryan
SUNY Upstate Medical University Clinical Campus at Binghamton
Binghamton, NY

Well, there is no function called "weeks" in chron. Funny that the
help mentions it.


You can, however, use normal POSIXct objects and extract the week with:

 dts <- dates(c("02/27/92", "02/27/92"))
 dts.posx <- as.POSIXct(dts)
 result   <- as.integer(format(dts.posx,format="%W"))



HTH
Jannis

--- Christopher W Ryan <cryan at binghamton.edu> schrieb am Di, 30.8.2011:
> Von: Christopher W Ryan <cryan at binghamton.edu>
> Betreff: [R] having trouble extracting week from chron object
> An: R-help at r-project.org
> Datum: Dienstag, 30. August, 2011 17:36 Uhr
> Running R 2.13.1 on Windows XP.
> I would like to get week of the year (1-52) for each date.
> 
> library(chron)
> dts <- dates(c("02/27/92", "02/27/92",
> "01/14/92","02/28/92", "02/01/92"))
> dts
> dts.chron <- as.chron(dts)
> dts.chron
> class(dts.chron)
> # all of these component extractions work:
> months(dts.chron)
> weekdays(dts.chron)
> years(dts.chron)
> quarters(dts.chron)
> # but weeks() doesn't seem to work
> weeks(dts.chron)
> 
> ?chron tells me: . . . The functions days(), months(),
> quarters(),
> years(), weeks(), weekdays(), hours(), minutes(), and
> seconds() take
> any chron object as input and extract the corresponding
> time interval
> . . . .
> 
> Any advice?
> 
> Thanks.
> 
> Chris Ryan
> SUNY Upstate Medical University Clinical Campus at
> Binghamton
> Binghamton, NY
> 
> ______________________________________________
> R-help at 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.
>

On Aug 30, 2011, at 1:36 PM, Christopher W Ryan wrote:
> Running R 2.13.1 on Windows XP.
> I would like to get week of the year (1-52) for each date.
>
> library(chron)
> dts <- dates(c("02/27/92", "02/27/92",
"01/14/92","02/28/92",
> "02/01/92"))
> dts
> dts.chron <- as.chron(dts)
> dts.chron
> class(dts.chron)
> # all of these component extractions work:
> months(dts.chron)
> weekdays(dts.chron)
> years(dts.chron)
> quarters(dts.chron)
> # but weeks() doesn't seem to work
It doesn't "work" for me either but since I also have the package
lubridate loaded, and ?weeks brings up a lubridate help page, I don't  
feel I have any right to complain. I get an error message.... what did  
you get?:

Error in Ops.dates(pieces$week, 7) : * not defined for chron objects

If I were posting I would also have had the good sense to include the  
output of sessionInfo().
> weeks(dts.chron)
Try type just:

  weeks  # I get a lubridate function.
>
> ?chron tells me:

Bur what does ?weeks tell you?
> . . . The functions days(), months(), quarters(),
> years(), weeks(), weekdays(), hours(), minutes(), and seconds() take
> any chron object as input and extract the corresponding time interval
> . . . .
>
> Any advice?
>
> Thanks.
>
> Chris Ryan
> SUNY Upstate Medical University Clinical Campus at Binghamton
> Binghamton, NY
>
> ______________________________________________
> R-help at 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.
David Winsemius, MD
West Hartford, CT

On Tue, Aug 30, 2011 at 1:36 PM, Christopher W Ryan
<cryan at binghamton.edu> wrote:
> Running R 2.13.1 on Windows XP.
> I would like to get week of the year (1-52) for each date.
>
> library(chron)
> dts <- dates(c("02/27/92", "02/27/92",
"01/14/92","02/28/92", "02/01/92"))
Try this:

as.numeric(cut(dts, "weeks"))


-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com