[SciPy-dev] Implementing a distance matrix between two sets of vectors concept

[David Cournapeau]

Peter Skomoroch wrote:
> I've rolled my own in the past.  If the vectors are really large and 
> you are holding a collection of them, you probably want to use a 
> sparse matrix data structure in either numpy or C.
Mmm, not sure to understand what you mean. The problem is that you have 
{u_1, ... , u_N} and {v_1, ..., v_M} vectors, and you want the distance 
for any possible combination {u_i, v_j}, which is a real (eg the actual 
size of the matrix in memory does not depends on the dimension of the 
data, only on N and M). I don't see how sparsity can help help here ?

David