[Numpy-discussion] Automatic matrices

Paulo Jose da Silva e Silva pjssilva at ime.usp.br
Fri Dec 15 18:21:37 CST 2006


Em Sex, 2006-12-15 às 23:37 +0100, Sven Schreiber escreveu:
> Paulo Jose da Silva e Silva schrieb:
> 
> > 
> > However, after trying to use the matrix class I have came across a major
> > roadblock: many numpy/scipy functions return an array by default and not
> > matrices. Then, we need then to add many conversion calls to the 'mat'
> > function in our code. This is also unconvenient.
> > 
> 
> scipy I don't know, but in numpy as a matrix user I'm glad that such
> behavior has been treated as bugs on the way to 1.0 -- so could you
> please send a list with the affected numpy functions?
> -sven

Ops...

I did not try to imply that there are some functions in numpy that
return array when receiving matrices. What I meant is that there are
functions in numpy that always return arrays. Hence they ask for an
explicit conversion to matrices. Good examples is the whole numpy.random
sub-module. So if you want a random matrix you need to type:

A = mat(numpy.random.rand(4,4))

Hence, a matrix user of numpy module still have to be aware of such
conversions.

Note that in my code, after importing numpy using the special module, I
can write

A = num.random.rand(4,4)

There is no special case.

best,

Paulo

Obs: I remember reading somewhere in the list that we can change the
behavior of numpy to make it return matrices as default, even in calls
for functions like zeros or ones. I don't have the reference now. Anyhow
I wanted a solution that can make any module play nice with matrices.




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