[R] Looking for a special date function in R

[Sergey Goriatchev]

Dear Gabor,

Thanks for that!
Still, it is not really similar to how EDATE works.
With julian(Sys.Date(), Sys.Date() - 10)  one moves 10 days back.
The problem is that I need to move by months, not by days, as months
have different number of days.
I need to come to the same day when I move backward or forward in
time, for example going back one month from today (21.01.2009) I need
to come to 21.12.2008.
I've read through your article in RNews 4/1 but still do not know how
to do what I need to do.

Regards,
Sergey

On Wed, Jan 21, 2009 at 10:44, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
> See ?julian
>
>> julian(Sys.Date(), Sys.Date() - 10) # 10
> [1] 10
> attr(,"origin")
> [1] "2009-01-11"
>
> and R News 4/1.
>
> On Wed, Jan 21, 2009 at 4:37 AM, Sergey Goriatchev <sergeyg at gmail.com> wrote:
>> Hello, everyone
>>
>> I wonder if R has something similar to Excel function
>> EDATE(start_date; months) which returns a serial number of the date
>> that is the indicated number of months before of after the start date.
>> Example (the second column EDATE(first_column; -6)):
>> 01.01.1999      01.07.1998
>> 02.02.1999      02.08.1998
>> 06.03.1999      06.09.1998
>>
>> I am working with a zoo object where the row names are dates and for
>> particular rows I need to find values that were recorded 6 months
>> before (or return NA if the date is before the timeseries start).
>>
>> Maybe someone knows a passable R function for that kind of operation?
>>
>> Thanks in advance for help!
>>
>> Best,
>> Sergey
>>
>> ______________________________________________
>> R-help at 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.
>>
>



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