[Rd] Dates in C api

Lee, Philip (IT) Phil.Lee at morganstanley.com
Mon Sep 22 21:41:42 CEST 2008


r-devel,

One other question just occurred to me - does R have any concept of
times alone?  I can see that there's dates, and datetimes (POSIXct etc),
but how should I represent 12:34:56 as just a time?

Thanks,
Phil

> -----Original Message-----
> From: Jeff Ryan [mailto:jeff.a.ryan at gmail.com]
> Sent: Wednesday, September 17, 2008 4:19 PM
> To: Lee, Philip (IT)
> Cc: r-devel at r-project.org
> Subject: Re: [Rd] Dates in C api
> 
> If you are looking for examples of handling dates/times (specifically
> POSIXct) within C code, the dev branch of xts has quite a bit of code
> now.
> 
> http://r-forge.r-
> project.org/plugins/scmsvn/viewcvs.php/dev/pkg/src/?root=xts
> 
> Assigning the class (or any attribute) within the C code will be much
> faster than doing it outside of C, at least in my experience with
> larger data.
> 
> setAttrib(ans, R_ClassSymbol, mkString("Date"))
> 
> HTH
> Jeff
> 
> On Wed, Sep 17, 2008 at 12:24 PM, Lee, Philip (IT)
> <Phil.Lee at morganstanley.com> wrote:
> > r-devel,
> >
> > I've been trying to write a C plugin for R, and I'm struggling to
> > understand how dates are represented.
> >
> > I can create a date in R:
> >> mydate<-as.Date(1, origin="1900-01-01") mydate
> > [1] "1900-01-02"
> >
> > When I pass my date to a plugin, though, it's type is that of a
real.
> > There doesn't seem to be a date type in Rinternals.h, is there a way
> to
> > recognize that a value is a date rather than a real?
> >
> > Equally, does anyone know if it's possible to create date values in
> the
> > C api?
> >
> > Thanks,
> > Phil Lee
> >
> > Philip Lee
> > Morgan Stanley | Technology
> > 750 Seventh Avenue, 12th Floor | New York, NY  10019
> > Phil.Lee at morganstanley.com
> > --------------------------------------------------------
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> 
> 
> 
> --
> Jeffrey Ryan
> jeffrey.ryan at insightalgo.com
> 
> ia: insight algorithmics
> www.insightalgo.com
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