Re: [ojAlgo-user] Interface analogous to Numpy?
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Re: [ojAlgo-user] Interface analogous to Numpy?
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From: Bruno D. <ab...@ma...> - 2012-04-20 12:43:54
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Dear Anders Peterson, > 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? Ok, let's see: http://docs.scipy.org/doc/numpy/reference/arrays.ndarray.html There are many fields which are all public. We could replace them by set- and get methods in the adapter. Most of them are used often. In consider only real, imag, __array_priority__ as optional: "ndarray.flags Information about the memory layout of the array. ndarray.shape Tuple of array dimensions. ndarray.strides Tuple of bytes to step in each dimension when traversing an array. ndarray.ndim Number of array dimensions. ndarray.data Python buffer object pointing to the start of the array's data. ndarray.size Number of elements in the array. ndarray.itemsize Length of one array element in bytes. ndarray.nbytes Total bytes consumed by the elements of the array. ndarray.base Base object if memory is from some other object. ndarray.dtype Data-type of the array's elements. ndarray.T Same as self.transpose(), except that self is returned if self.ndim < 2. ndarray.real The real part of the array. ndarray.imag The imaginary part of the array. ndarray.flat A 1-D iterator over the array. __array_priority__" ndarray.strides and ndarray.shape are the most important for creating views. We would need an additional offset, because there are no pointers to array parts in Java. For instance a vector-view of the third column of an m x n non-view, row-order matrix A would roughly look like this: shape = tuple(m, 1) offset = 2 * m base = the same array as in A, no copy strides = tuple(n) size = m ndim = 1 The transpose of the same matrix would roughly look like this: shape = tuple(m, n) offset = 0 base = the same array as in A, no copy strides = the reverse of A.strides = tuple(1, n) size = the same as in A ndim = the same as in A = 2 If A is already a view there will be other values in offset and strides. These are for interfacing C programs. I hope they are not used too often in common Numpy programs. Stefan Richthofer, what do you think? "The Array Interface. __array_interface__ Python-side of the array interface __array_struct__ C-side of the array interface" ndarray.ctypes An object to simplify the interaction of the array with the ctypes module." > Currently ojAlgo supports double, BigDecimal, ComplexNumber and > RationalNumber elements with the ArrayAnyD class. Are other types required? Integers are quite common. The other types (there are many of them) could be added later: http://docs.scipy.org/doc/numpy/reference/arrays.dtypes.html#arrays-dtypes > 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? Thanks, Git would be nice, Subversion is also ok. Best regards Bruno Daniel Anders Peterson wrote: > 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? > > Currently ojAlgo supports double, BigDecimal, ComplexNumber and RationalNumber elements with the ArrayAnyD class. Are other types required? > > 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? > > /Anders > > > 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. >>>>>> >>>>>> >>>>> ------------------------------------------------------------------------------ >>>>>> For Developers, A Lot Can Happen In A Second. >>>>>> Boundary is the first to Know...and Tell You. >>>>>> Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! >>>>>> http://p.sf.net/sfu/Boundary-d2dvs2 >>>>>> _______________________________________________ >>>>>> ojAlgo-user mailing list >>>>>> ojA...@li... >>>>>> https://lists.sourceforge.net/lists/listinfo/ojalgo-user >>>>> >>>>> ------------------------------------------------------------------------------ >>>>> For Developers, A Lot Can Happen In A Second. >>>>> Boundary is the first to Know...and Tell You. >>>>> Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! >>>>> http://p.sf.net/sfu/Boundary-d2dvs2 >>>>> _______________________________________________ >>>>> ojAlgo-user mailing list >>>>> ojA...@li... >>>>> https://lists.sourceforge.net/lists/listinfo/ojalgo-user >>>> >>>> -- >>>> NEU: FreePhone 3-fach-Flat mit kostenlosem Smartphone! >>>> Jetzt informieren: http://mobile.1und1.de/?ac=OM.PW.PW003K20328T7073a >>>> >>>> ------------------------------------------------------------------------------ >>>> For Developers, A Lot Can Happen In A Second. >>>> Boundary is the first to Know...and Tell You. >>>> Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! >>>> http://p.sf.net/sfu/Boundary-d2dvs2 >>>> _______________________________________________ >>>> ojAlgo-user mailing list >>>> ojA...@li... >>>> https://lists.sourceforge.net/lists/listinfo/ojalgo-user >>>> >>>> >>> >>> >>> ------------------------------------------------------------------------------ >>> For Developers, A Lot Can Happen In A Second. >>> Boundary is the first to Know...and Tell You. >>> Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! >>> http://p.sf.net/sfu/Boundary-d2dvs2 >>> _______________________________________________ >>> ojAlgo-user mailing list >>> ojA...@li... >>> https://lists.sourceforge.net/lists/listinfo/ojalgo-user >> >> ------------------------------------------------------------------------------ >> For Developers, A Lot Can Happen In A Second. >> Boundary is the first to Know...and Tell You. >> Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! >> http://p.sf.net/sfu/Boundary-d2dvs2 >> _______________________________________________ >> ojAlgo-user mailing list >> ojA...@li... >> https://lists.sourceforge.net/lists/listinfo/ojalgo-user >> >> > > > ------------------------------------------------------------------------------ > For Developers, A Lot Can Happen In A Second. > Boundary is the first to Know...and Tell You. > Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! > http://p.sf.net/sfu/Boundary-d2dvs2 > _______________________________________________ > ojAlgo-user mailing list > ojA...@li... > https://lists.sourceforge.net/lists/listinfo/ojalgo-user |
