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
"1991-10-07 10:35:00" changed it by: w$d<-as.POSIXct(w$date.time) Now I can add an offset of 92 days w$w.year<-as.POSIXct(w$d+7948800) and have the years correspond to the "water year." Now I wish to obtain some means by something like: waterT<-aggregate(w$value[w$param.name=="Temperature"], list(w$w.year[w$param.name=="Temperature"]),mean) Except that I need to work on the year and being a neophyte in date arithmetic I'm not finding a working method. TIA Clint -- Clint Bowman INTERNET: [EMAIL PROTECTED] Air Quality Modeler INTERNET: [EMAIL PROTECTED] Department of Ecology VOICE: (360) 407-6815 PO Box 47600 FAX: (360) 407-7534 Olympia, WA 98504-7600 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
