[R] Define a variable on a non-standard year interval (Water Years)

[Gabor Grothendieck]

On Mon, Jun 11, 2012 at 1:22 PM, Sam Albers <tonightsthenight at gmail.com> wrote:
> Hello,
>
> I am trying to define a different interval for a "year". In hydrology,
> a "water year" is defined as the period between October 1st and
> September 30 of the following year. I was wondering how I might do
> this in R. Say I have a data.frame like the following and I want to
> extract a variable with the water year specs as defined above:
>
> df<-data.frame(Date=seq(as.Date("2000/10/1"), as.Date("2003/9/30"), "days"))
>
> ## Extract the normal year
> df$year <- factor(format(as.Date(df$Date), "%Y"))
>
> So the question is how might I define a variable that extends from
> October 1st to September 30th rather than the normal January 1st to
> December 31st?
>

See this:

https://stat.ethz.ch/pipermail/r-help/2004-June/052952.html


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