[Numpy-discussion] Deprecating matrices.

[Ralf Gommers]

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.

Ralf
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