[R] Select range of dates

[Gabor Grothendieck]

Here are three alternative ways to get the fiscal year as a numeric
value assuming:
dd <- as.Date(x$Date,"%d/%m/%Y")

# add one to year if month is past March
as.numeric(format(dd, "%Y")) + (format(dd, "%m") > "03")

# same but using POSIXlt
# (Even though there are no time zones involved I have seen
# situations where the time zone nevertheless crept in
# where one would least expect it so even though I believe
# this is correct I would nevertheless triple check
# all your results if you use this one)
with(as.POSIXlt(dd), 1900 + year + (mon > 2))

# this makes use of the zoo yearqtr class
# which represents dates as year + 0, .25, .5 or .75 for
# the four quarters
library(zoo)
as.numeric(ceiling(as.yearqtr(dd)))



On 10/7/06, Ian Broom <broomian at gmail.com> wrote:
> Hello,
>
> This is likely fairly silly question, and I apologize to whomever takes the
> time to respond.
>
> I am a relatively new user of R, on Windows XP, version 2.3.1.
>
> Say I have a data table that looks like the following:
>
> x
>         Date Location  Amount  Blue Green
> 1  01/01/2001  Central    1817  TRUE FALSE
> 2  01/02/2001  Central   20358 FALSE  TRUE
> 3  05/08/2001  Central   16245 FALSE  TRUE
> 4  02/02/2002  Western     112  TRUE FALSE
> 5  21/03/2002  Western   98756  TRUE FALSE
> 6  01/04/2002  Western 1598414 FALSE  TRUE
> 7  07/01/2001  Western    1255 FALSE  TRUE
> 8  20/10/2003  Central   16289  TRUE FALSE
> 9  21/10/2003  Eastern   10000 FALSE  TRUE
> 10 22/10/2003  Eastern   98737 FALSE  TRUE
> 11 23/10/2003  Eastern  198756  TRUE FALSE
> 12 24/10/2003  Eastern   98756 FALSE  TRUE
> 13 25/10/2003  Eastern   65895  TRUE FALSE
> 14 26/10/2003  Eastern 2142266 FALSE  TRUE
> 15 27/10/2003    North   98756  TRUE FALSE
> 16 28/10/2003    North  548236 FALSE  TRUE
>
> and I want to do some summaries by Fiscal year (or FY quarter).
> Reading manuals and such, I cobbled this less than satisfactory bit together
> to start to build a factor representing a fiscal year split:
>
> y<-as.Date(x$Date,"%d/%m/%Y")
> y<-as.matrix(y)
> y$FY0203<-ifelse((y>=(as.Date("2002-03-21")))&(y<=(as.Date
> ("2003-04-01"))),"TRUE","FALSE")
>
> the values seem correct, but aside from ugly, the data is not in the proper
> format - with some more effort I might fix that... But my question is: is
> there a more simple function available to select a range of dates? Or, at
> least, a more elegant approach?
>
>        [[alternative HTML version deleted]]
>
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