Re: [ojAlgo-user] Interface analogous to Numpy?

[Stefan R. <Ste...@gm...>]

Hello together,
I also often thought about the idea to have a numpy-substitute for java, but always feared the enormous effort related to it.

Be aware of the high Potential of the idea. 

Having a numpy substitute in java would enable a huge amount of scientific python-code to run directly in java via jython (maybe with a slight modification of the imports).

Jython's main issue keeping it from being very useful is, that it does not support external (native) libraries written for Python.

I regard numpy as one of the most important of these and I believe, that a significant amount of scientific python-code has numpy as the only non-python-core-dependency and thus could run via jython, if there was a numpy for java.

Maybe you could consider a cooperation with the jython-developers at http://www.jython.org ...?
It should be highly in their interest to have a numpy implementation for java.


Greetings

Stefan



-------- Original-Nachricht --------
> Datum: Thu, 19 Apr 2012 13:56:49 +0200
> Von: Anders Peterson <an...@op...>
> An: oja...@li...
> Betreff: Re: [ojAlgo-user] Interface analogous to Numpy?

> Short anser is yes, but you have to be more specific regarding what you
> want/need and willing to do some of the work yourself.
> 
> ojAlgo has multi/any-dimensional arrays:
> 
> http://ojalgo.org/generated/org/ojalgo/array/ArrayAnyD.html
> 
> Frankly I don't really know what to do with them. I tend to only use 1- or
> 2-dimensional data structures. I created them because they were a
> generalization of what I needed that *could* become useful.
> 
> I guess the various MatrixStore implementations and the
> MatrixStore.Builder does much of what you want, but only for 2-dim arrays (and with wrong
> syntax).
> 
> http://ojalgo.org/generated/org/ojalgo/matrix/store/MatrixStore.html
> http://ojalgo.org/generated/org/ojalgo/matrix/store/MatrixStore.Builder.html
> 
> In ojAlgo the description of the array shape/structure is fixed as defined
> in AccessUtils
> 
> http://ojalgo.org/generated/org/ojalgo/access/AccessUtils.html
> 
> Would that need to be changed? (I hope not.)
> 
> /Anders
> 
> 
> On 19 apr 2012, at 11:35, B.D. wrote:
> 
> > Dear developers,
> > 
> > I'm primarily interested in Machine Learning and Data analysis. Thanks
> for the
> > good work, I appreciate the ojAlgo library very much! However, most new
> > algorithms and applications in this field are still written in Python
> for
> > Numpy/Scipy, not Java. I just had an idea:
> > 
> > If one could offer classes/interfaces in pure Java with similar
> functionality
> > and names as in
> > 
> > http://docs.scipy.org/doc/numpy/reference/ ,
> > 
> > in particular ndarray
> > 
> > http://docs.scipy.org/doc/numpy/reference/arrays.ndarray.html
> > 
> > (e.g. strides in matrices and vectors, transposition, reshaping of
> matrices as
> > a view without copying, many views on the same matrix data), then one
> could
> > rather easily translate Python programs using Numpy to pure Java without
> > reinventing the wheel and offer the excellent Python software for Java
> under
> > the same license as the original.
> > 
> > There are syntax limitations in Java, so
> > 
> > A[2:5, :]
> > 
> > would have to be translated to some intutive name or even a crazy
> mnemonic like
> > 
> > A.viewI_c_icI(2, 5)
> > 
> > (I = [ or ],
> > i = comma,
> > c = colon,
> > _ = slots for the arguments).
> > 
> > What do you think?
> > 
> > Best regards
> >  B.D.
> > 
> >
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