[Numpy-discussion] matrix default to column vector?

Olivier Verdier zelbier at gmail.com
Fri Jun 5 11:38:40 EDT 2009

I agree. It would be a good idea to have matrices out of numpy as a
standalone package.
Indeed, having matrices in the numpy core comes at a pedagogical cost.
Newcomers (as I once was) do not know which to use. Matrix or array? It
turns out that the vast majority of numpy/scipy modules use arrays, so
arrays is the preferred way to go.

It would thus be clearer to have arrays in numpy and matrices available as
an external package.

Besides, I think matrices can be pretty tricky when used for teaching. For
instance, you have to explain that all the operators work component-wise,
except the multiplication! Another caveat is that since matrices are always
2x2, the "scalar product" of two column vectors computed as " x.T * y" will
not be a scalar, but a 2x2 matrix. There is also the fact that you must cast
all your vectors to column/raw matrices (as in matlab). For all these
reasons, I prefer to use arrays and dot for teaching, and I have never had
any complaints.

== Olivier

2009/6/4 Tommy Grav <tgrav at mac.com>

> On Jun 4, 2009, at 5:41 PM, Alan G Isaac wrote:
> > On 6/4/2009 5:27 PM Tommy Grav apparently wrote:
> >> Or the core development team split the matrices out of numpy and
> >> make it
> >> as separate package that the people that use them could pick up and
> >> run with.
> >
> >
> > This too would be a mistake, I believe.
> > But it depends on whether a goal is to
> > have more people use NumPy.  I believe
> > the community will gain from growth.
> >
> > In sum, my argument is this:
> > Keeping a matrix object in NumPy has substantial
> > benefits in encouraging growth of the NumPy
> > community, and as far as I can tell, it is
> > imposing few costs.  Therefore I think there is
> > a very substantial burden on people who propose
> > removing the matrix object to demonstrate
> > just how the NumPy community will benefit from
> > this change.
> This is a perfectly valid argument. I am actually quite happy with the
> numpy package as it is (I work in astronomy), I was just pointing out
> that if there are few of the core numpy people interested in maintaing
> or upgrading the matrix class one solution might be to make it a
> scipy-like package that easily can be installed on top of numpy, but
> where the code base might be more accessible to those that are
> interested in matrices, but feel that numpy is a daunting beast to
> tackle.
> Some sense of ownership of a matrixpy package might encourage more
> people to contribute.
> Just an idea ;-)
> Tommy
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