On Thu, Sep 11, 2008 at 2:26 PM, Jeffrey J. Hallman <[EMAIL PROTECTED]> wrote: > Look at the ti (Time Index) class in package tis. Here's some examples I > just did: >> x <- Sys.Date() >> x > [1] "2008-09-11" >> ti(x, "wsaturday") ## a ti for the week that x falls into > [1] 20080913 > class: ti >> ti(x + 1, "wsaturday") - 1 ## ti for the latest complete week > [1] 20080906 > class: ti >> as.Date(ti(x + 1, "wsaturday") - 1) ## as a Date > [1] "2008-09-06" >> ymd(ti(x + 1, "wsaturday") - 1) ## or just the yyyymmdd number > [1] 20080906
Hmmm: dates <- structure(c(8516, 8544, 8568, 8596, 8609, 8666, 8701, 8750, 8754, 8798, 8811, 8817, 8860, 8873, 8918, 8931, 8966, 9020, 9034, 9056 ), class = "Date") > range(dates) [1] "1993-04-26" "1994-10-18" > as.Date(ti(range(dates), "monthly")) [1] "1993-04-30" "1994-10-31" > as.Date(ti(range(dates), "annual")) [1] "1993-12-31" "1994-12-31" What's the easiest way to control whether the dates are rounded up or down? And to get the starting period I just subtract one from the ti object and then add one to the Date object? Is there any standard way to do multiples of periods? (e.g. 3 weeks, 4 days). And is the finest resolution of a ti object a day? I don't think I see any periods less than that in the output of tif() Hadley -- http://had.co.nz/ ______________________________________________ R-help@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.
