[Numpy-discussion] matrices in 1.1
Stéfan van der Walt
stefan@sun.ac...
Sat Mar 22 10:40:55 CDT 2008
On Sat, Mar 22, 2008 at 4:40 PM, Stéfan van der Walt <sjvdwalt@gmail.com> wrote:
> Hi Alan
>
>
> On Fri, Mar 21, 2008 at 7:11 PM, Alan G Isaac <aisaac@american.edu> wrote:
> > On Fri, 21 Mar 2008, Stéfan van der Walt apparently wrote:
> > > The last I remember, we considered adding RowVector,
> > > ColumnVector and letting slices out of a matrix either be
> > > one of those or a matrix itself.
> >
> > There was a subsequent discussion.
>
> If there was, I still don't remember the result being the one you
> suggested (could be my bad memory, but maybe you can post a link as a
> reminder).
>
>
> > > I simply don't see a Matrix as a container of ndarrays
> > That is hardly an argument.
>
> Not an argument, just my opinion or perspective. In the matrix world,
> everything has a minimum dimension of 2, so I don't see how you can
> contain ndarrays in a matrix.
>
>
> > Remember, any indexing that when applied to an 2d array
> > would produce a 2d array will when applied to a matrix
> > still produce a matrix.
>
> Sure.
>
>
> > This is really just principle of least surprise.
>
> Or not, depending on where you come from. I'd expect indexing
> operations that produce 1D-arrays on ndarrays to produce 2D-arrays on
> matrices.
>
>
> > PS Are you a *user* of matrices?
>
> No, I'm not (I love the consistency of the ndarray approach, and
> broadcasting always does the Right Thing (TM)). Although I do
> sometimes use matrices when I'm lazy to apply dot, i.e.
>
> A,B,C,D = [np.asmatrix(a) for a in [arr1,arr2,arr3,arr4]]
> result = (A*B*C*D).A
>
> Regards
> Stéfan
>
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