[R] finding the year of a date

[Gabor Grothendieck]

On Mon, Oct 25, 2010 at 12:38 PM, Dimitri Liakhovitski
<dimitri.liakhovitski at gmail.com> wrote:
> I know that I can use as.yearmon in the package "zoo" to find the year
> and the month of a date.
> I can use as. yearqtr to find the year and the quarter.
> But how can one find just the year of a date?
>
> Thanks a lot!

Here are three ways.  The first uses the fact that the year is the
whole number part of a yearmon object.

> library(zoo)
> d <- Sys.Date()
> floor(as.numeric(as.yearmon(d)))
[1] 2010
>
> as.numeric(format(d, "%Y"))
[1] 2010
>
> as.POSIXlt(d)$year + 1900
[1] 2010

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