On Mon, Feb 10, 2014 at 10:09 AM, Alan G Isaac <alan.is...@gmail.com> wrote:
> On 2/9/2014 5:55 PM, alex wrote: > > I'm working on the same kinds of problems in scipy development > > (functions involving sparse matrices and abstract linear operators) > > > And how is numpy's matrix object getting in your way? > Your initial post simply treated the desirability of > deprecation as a given and did not lay out reasons. > A strong reason would be e.g. if the matrix object > is creating a serious maintenance headache. Eliminating > this should be a big enough gain to offset any lost interest > in numpy from users of Matlab, GAUSS, IDL etc. from the > disappearance of a user-friendly notation. > > I accept that a numpy matrix has some warts. In the past, > I've proposed changes to address these. E.g., > https://www.mail-archive.com/numpy-discussion@scipy.org/msg06780.html > However these went nowhere, so effectively the status quo was > defended. I can live with that. > > A bit of the notational advantage of the `matrix` object was undercut > by the addition of the `dot` method to arrays. just another one that make arrays nicer (although I'm on old versions and don't use it yet): keepdims option for reduce operations, like mean. demean each row ? Josef > If `matrix` is deprecated, > I would hope that a matrix-power method would be added. (One that works > correctly with boolean arrays and has a short name.) I ideally an inverse > method would be added as well (with a short name). I think adding the > hermitian transpose as `.H()` already has some support, but I forget its > current > status. > > Right now, to give a simple example, students can write a simple projection > matrix as `X * (X.T * X).I * X.T` instead of > `X.dot(la.inv(X.T.dot(X))).dot(X.T)`. > The advantage is obvious and even bigger with more complex expressions. > If we were to get `.I` for matrix inverse of an array (which I expect to be > vociferously resisted) it would be `X.dot(X.T.dot(X).I).dot(X.T)` which > at the moment I'm inclined to see as acceptable for teaching. (Not sure.) > > Just to forestall the usual "just start them with arrays, eventually > they'll > be grateful" reply, I would want to hear that suggestion only from someone > who has used it successfully with undergraduates in the social sciences. > > Alan Isaac > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion >
_______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
