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

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

> Getting some small application that (only) depends on NumPy to run on
> Jython would be a proof of concept.
> 
> I looked at the ndarray "interface". Some things look a bit scary... Are
> all the attributes and methods mentioned on that page public and
> non-optional?

In fact I did not really have a look at that interface yet.
Once I tried to setup a kind of "jumpy" by using original numpy through JNI. But for this I focused on the communication between python and its native extensions, especially numpy. So it was another layer of interfaces, I dived into (that were mainly the headers occuring in python.h).


> Currently ojAlgo supports double, BigDecimal, ComplexNumber and
> RationalNumber elements with the ArrayAnyD class. Are other types required?

I think, numpy is also capable of having integer-matrices/arryas/however, but no RationalNumber (in the sense of an integer-tuple (numerator, denominator)). Maybe we can use RationalNumber with denominator=1, but including integer matrices into the support might be of better performance.

There is another thing about python/numpy/jython. Because python/numpy supports unsigned long and double primitives, the de-facto number range of these types can not be fully covered by java primitive types. Jython covers this issue by mapping these types to BigNumber-types. I'm not sure, whether there could arise any problems from this for "jumpy" - just keep it in mind.

> How about I create a sandbox version control system (for experimental
> code) over at http://code.google.com/p/ojalgo/
> 
> What do you prefer: Subversion, Git or Mercurial?

I think its a nice idea, though I can't promise that I will have very much time for this project. From work I only know Mercurial, so I don't have an educated opinion, which one is best.


Stefan



> On 19 apr 2012, at 22:21, B.D. wrote:
> 
> > Dear Mr. Peterson,
> > 
> >> Don't talk too much - just do it. Start with the most simple case.
> > 
> > yes, you're right. I think this is a nice collection of simple unit
> tests for
> > me: http://www.scipy.org/Numpy_Example_List
> > 
> > See you later,
> >  B.D.
> > 
> > 
> > Anders Peterson wrote:
> >> Let's call it Jumpy...
> >> 
> >> Since I'm not a python/jython/numpy/scipy user I think someone else
> should take the lead here.
> >> 
> >> Don't talk too much - just do it. Start with the most simple case.
> >> 
> >> I'm definitely interested in ways to make ojAlgo more useful.
> >> 
> >> /Anders
> >> 
> >> 
> >> On 19 apr 2012, at 15:39, Stefan Richthofer wrote:
> >> 
> >>> 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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> >> 
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> > 
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> > 
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