[Numpy-discussion] matrix wart

[Konrad Hinsen]

On 22.02.2008, at 01:10, Alan G Isaac wrote:

> Someone once pointed out on this list that one might
> consider a matrix to be a container of 1d vectors.  For NumPy,
> however, it is natural that it be a container of 1d arrays.
> (See the discussion for the distinction.)

If I were to design a Pythonic implementation of the mathematical  
concept of a matrix, I'd implement three classes: Matrix,  
ColumnVector, and RowVector. It would work like this:

m = Matrix([[1, 2], [3, 4]])

m[0, :] -->  ColumnVector([1, 3])
m[:, 0] --> RowVector([1, 2])

m[0,0] --> 1  # scalar

m.shape --> (2, 2)
m[0].shape --> (2,)

However, the matrix implementation in Numeric was inspired by Matlab,  
where everything is a matrix. But as I said before, Python is not  
Matlab.

Konrad.