[R] Base function for flipping matrices

[Claudia Beleites]

Hadley,

I started to throw some functions that I needed to be extended to arrays
together as package arrayhelpers. If you consider that a good home for
the new functions, they would be more than welcome.

Currently I have the package at r-forge, but I wouldn't mind github,
either (so far I just use git-svn). Unit tests use svUnit, not testthat,
though.

Happy new year to everyone,

Claudia




Am 02.01.2012 18:38, schrieb Richard M. Heiberger:
> Hadley,
> 
> Your request is reminding me of the analysis of aray functions in Philip S
> Abrams dissertation
> http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-r-114.pdf
> AN APL MACHINE
> 
> The section that starts on page 17 with this paragraph is the one that
> immediately applies
> 
> C. The Standard Form for Select Expressions
> 
> In this section the selection operators considered are take, drop, reversal,
> transpose, and subscripting by scalars or _J-vectors. Because of the
> similarity
> among the selection operators, we might expect that an expression
> consisting only
> of selection operators applied to a single array could be expressed
> equivalently in
> terms of some simpler set of operators. This expectation is fulfilled in the
> standard form for select expressions, to be discussed below.
> 
> I look forward to seeing where you take this in R.
> 
> Rich
> 
> On Mon, Jan 2, 2012 at 8:38 AM, Hadley Wickham <hadley at rice.edu> wrote:
> 
>>> But if not,  it seems to me that it should be added as an array method
>>> to ?rev with an argument specifying which indices to rev() over.
>>
>> Yes, agreed.  Sometimes arrays seem like something bolted onto R that
>> is missing a lot of functionality.
>>
>> Hadley
>>
>> --
>> Assistant Professor / Dobelman Family Junior Chair
>> Department of Statistics / Rice University
>> http://had.co.nz/
>>
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>>
> 
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> 
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-- 
Claudia Beleites
Spectroscopy/Imaging
Institute of Photonic Technology
Albert-Einstein-Str. 9
07745 Jena
Germany

email: claudia.beleites at ipht-jena.de
phone: +49 3641 206-133
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