[Numpy-discussion] Deprecating matrices.

[Charles R Harris]

On Sat, Jan 7, 2017 at 2:29 PM, Ralf Gommers <ralf.gommers at gmail.com> wrote:

>
>
> On Sun, Jan 8, 2017 at 9:31 AM, Todd <toddrjen at gmail.com> wrote:
>
>>
>>
>> On Jan 6, 2017 20:28, "Ralf Gommers" <ralf.gommers at gmail.com> wrote:
>>
>>
>>
>> On Sat, Jan 7, 2017 at 2:21 PM, CJ Carey <perimosocordiae at gmail.com>
>> wrote:
>>
>>>
>>> On Fri, Jan 6, 2017 at 6:19 PM, Ralf Gommers <ralf.gommers at gmail.com>
>>> wrote:
>>>
>>>> This sounds like a reasonable idea. Timeline could be something like:
>>>>
>>>> 1. Now: create new package, deprecate np.matrix in docs.
>>>> 2. In say 1.5 years: start issuing visible deprecation warnings in numpy
>>>> 3. After 2020: remove matrix from numpy.
>>>>
>>>> Ralf
>>>>
>>>
>>> I think this sounds reasonable, and reminds me of the deliberate
>>> deprecation process taken for scipy.weave. I guess we'll see how successful
>>> it was when 0.19 is released.
>>>
>>> The major problem I have with removing numpy matrices is the effect on
>>> scipy.sparse, which mostly-consistently mimics numpy.matrix semantics and
>>> often produces numpy.matrix results when densifying. The two are coupled
>>> tightly enough that if numpy matrices go away, all of the existing sparse
>>> matrix classes will have to go at the same time.
>>>
>>> I don't think that would be the end of the world,
>>>
>>
>> Not the end of the world literally, but the impact would be pretty major.
>> I think we're stuck with scipy.sparse, and may at some point will add a new
>> sparse *array* implementation next to it. For scipy we will have to add a
>> dependency on the new npmatrix package or vendor it.
>>
>> Ralf
>>
>>
>>
>>> but it's definitely something that should happen while scipy is still
>>> pre-1.0, if it's ever going to happen.
>>>
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>>>
>>>
>>
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>>
>>
>> So what about this:
>>
>> 1. Create a sparse array class
>> 2. (optional) Refactor the sparse matrix class to be based on the sparse
>> array class (may not be feasible)
>> 3. Copy the spare matrix class into the matrix package
>> 4. Deprecate the scipy sparse matrix class
>> 5. Remove the scipy sparse matrix class when the numpy matrix class
>>
>
> It looks to me like we're getting a bit off track here. The sparse
> matrices in scipy are heavily used, and despite rough edges pretty good at
> what they do. Deprecating them is not a goal.
>
> The actual goal for the exercise that started this thread (at least as I
> see it) is to remove np.matrix from numpy itself so users (that don't know
> the difference) will only use ndarrays. And the few users that prefer
> np.matrix for teaching can now switch because of @, so their preference
> should have disappeared.
>
> To reach that goal, no deprecation or backwards incompatible changes to
> scipy.sparse are needed.
>

What is the way forward with sparse? That looks like the biggest blocker on
the road to a matrix free NumPy. I don't see moving the matrix package
elsewhere as a solution for that.

Chuck
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