[SciPy-Dev] Sparse boolean specification

J.J. Green j.j.green@gmx...
Mon Apr 22 11:08:24 CDT 2013

Pauli Virtanen wrote:

> The drawback here is that `==`, `<=`, `>=` become somewhat
> useless for sparse matrices as it tends to produce matrices
> filled with True. But I think this cannot be helped.

Can't you then just have a sparse structure which also hold
the 'empty' value (whether it be true or false), then the 
non-empty cells are the opposite value.  Thus !a just changed
the 'empty' value and leaves the matrix structure otherwise
unchanged ?

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