[R] Error in str(its-object)

[Armstrong, Whit]

I'll update ITS to include that signature.

Right now, the only signature for Arith is:
signature(e1="its",e2="its").

Thx,
Whit


> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Martin Maechler
> Sent: Tuesday, November 14, 2006 11:24 AM
> To: Stefan Albrecht
> Cc: r-help at stat.math.ethz.ch
> Subject: Re: [R] Error in str(its-object)
> 
> >>>>> "StAl" == Albrecht, Dr Stefan (AZ Private Equity 
> Partner) <stefan.albrecht at apep.com>
> >>>>>     on Tue, 14 Nov 2006 15:36:45 +0100 writes:
> 
>     StAl> Dear all, on my Windows XP R 2.4.0 version with
>     StAl> Package its version 1.1.4 I have a problem with str()
>     StAl> applied on an its-object after a simple matrix
>     StAl> manipulation on the its object (see below).  I am not
>     StAl> sure, whether this a problem with my application, its
>     StAl> or str().
>  
> I'd say mainly with its, and then with R internal arithmetic.
> str() actually reveals that the object you produce is not 
> ``valid'' anymore in a certain sense (see below).
> 
>     StAl> .......... But its object should be able to handle 
> simple matrix
>     StAl> multiplications, even if the result is a matrix.  Any
>     StAl> help is greatly appreciated.
>  
> "/ 1" is not a simple multiplication. 
> But I agree that package
> "its" (which you failed to mention) should make sure that
>       ' <itsObj> / 1 '
> 
> should work -- which it does not.  Here is a reproducible 
> example script - extended from your transcript :
> 
> --------------------------------------------------------------
> ------------
> 
> (mat <- matrix(1:6, 2,3,
>                
> dimnames=list(c("2003-01-01","2003-01-04"),letters[1:3])))
> library(its)
> (im <- its(mat))
> str(im)
> 
> isS4(im)    # TRUE, of course,  but ..
> isS4(im / 1)# FALSE !!!
> 
> ## even though
> class(im / 1)
> ## shows
> ## [1] "its"
> ## attr(,"package")
> ## [1] "its"
> 
> ## and the reason comes from
> selectMethod("/", signature(e1 = "its", e2 = "numeric")) ## 
> -> .Primitive("/")
> 
> --------------------------------------------------------------
> ------------
> 
> So what happens is that the builtin arithmetic *does* work on 
> the .Data slot automatically -- as it should IIRC the green 
> book on this topic.
> 
> What the builtin arithmetic *fails* to do, is keeping the 
> S4-object bit.
> --> I'll post a version of this to R-devel, since I think we
> should consider improving the current behavior here.
> 
> For the current version of R, the maintainer of "its" should 
> really define "Arith" methods for signature("its", "numeric") 
> and signature("numeric", "its").
> 
> Martin Maechler, ETH Zurich
> 
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> 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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