[R] Aggregating on Water Year Rather Than Calendar Year
macq at llnl.gov
Wed Jun 16 22:57:54 CEST 2004
It's not clear where your problem is.
Did w$w.year come out wrong?
Or did the aggregate() function fail?
For getting the water year, I would do it differently:
(this is for a U.S. English locale, and minimally tested)
tmp <- as.POSIXlt(w$d)$year+1900
w$w.year <- ifelse( format(w$d,'%b') %in% c('Oct','Nov','Dec'), tmp+1, tmp)
Then you can do things like
to help find out if w.year came out like it should.
You'll have to provide error messages or something if the problem is
with using aggregate().
At 11:21 AM -0700 6/16/04, Clint Bowman wrote:
>The US water year extends from 01 October yyyy-1 through 30 September yyyy
>and is referenced by the year starting on the included 01 January yyyy.
>I'd like to be able to find the annual means for the water year. To do so
>I've taken the input date-time, which is in the usual format
>changed it by:
>Now I can add an offset of 92 days
Try w$w.year <- w$d+7948800
>and have the years correspond to the "water year."
>Now I wish to obtain some means by something like:
>Except that I need to work on the year and being a neophyte in date
>arithmetic I'm not finding a working method.
>Clint Bowman INTERNET: clint at ecy.wa.gov
>Air Quality Modeler INTERNET: clint at math.utah.edu
>Department of Ecology VOICE: (360) 407-6815
>PO Box 47600 FAX: (360) 407-7534
>Olympia, WA 98504-7600
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
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