[R] Extracting year from a date object

[Prof Brian Ripley]

See ?weekdays, which says

Note:

      Other components such as the day of the month or the year are very
      easy to compute: just use 'as.POSIXlt' and extract the relevant
      component.

so

> as.POSIXlt(MyDate)$year+1900
[1] 1994

is how you are expected to do it.

On Tue, 6 Oct 2009, joris meys wrote:

> Hi all,
>
> this one left me a bit puzzled, as I don't seem to find a function to
> perform this easily. I must have overlooked the obvious, so sorry in
> advance.
>
> I have a list of dates in numerical format (i.e. 34576), defined as
> the number of days that passed since january 1st 1900. So I apply the
> function :
>
>> MyDate <-as.Date(34576,origin="1900-01-01")
>> MyDate
> [1] "1994-09-01"
>
> But then I want to do something like :
> MyYear <- a.year.function(MyDate)
>
> MyYear should have the numerical value 1994. Alas, I don't find any
> function like that. I know I can take a substring of MyDate and
> convert to numeric, or even use the function "seq()" :
>
>> length ( seq ( as.Date("1900-01-01"), MyDate, "years" ) ) + 1900 - 1
> [1] 1994
>
> but that seems quite a way around. Can somebody tell me where the
> appropriate function is hiding?
> Thank you in advance.
> Joris
>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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