Hi all<div><br></div><div>I am trying to create a subclass of the sparse matrix class in scipy, to add some extra methods I need. </div><div><br></div><div>I have tried to follow the guide on: <a href="http://www.scipy.org/Subclasses">http://www.scipy.org/Subclasses</a> but without much luck, the view method does not exist for the sparse matrix class. Below is a script I have created</div>

<div><br></div><div>-----------------</div><div><br></div><div><div>#!/usr/bin/env python</div><div><br></div><div>from scipy.sparse.csr import csr_matrix as spmatrix</div><div><br></div><div>class sparsematrix_addons(spmatrix):</div>

<div>    &quot;&quot;&quot;</div><div>    subclass for standard scipy sparse class to add missing functionality</div><div>    &quot;&quot;&quot;</div><div><br></div><div>    def __new__(cls, matrix):</div><div>        obj = spmatrix.__init__(cls, matrix)</div>

<div>        return obj</div><div><br></div><div>    def square_spmat(self, M):</div><div>        return M ** 2</div><div><br></div><div>    def ravel_spmat(self, M):</div><div>        pass</div><div><br></div><div>if __name__ == &#39;__main__&#39;:</div>

<div><br></div><div>    import numpy as np</div><div><br></div><div>    x = (np.random.rand(10, 10) * 2).astype(int).astype(float)</div><div>    xsp = sparsematrix_addons(x)</div></div><div><br></div><div>--------------------</div>

<div><br></div><div>However, this generates the following error:</div><div><br></div><div>TypeError: unbound method __init__() must be called with csr_matrix instance as first argument (got type instance instead)</div><div>

<br></div><div>I am not strong in python OOP, or OOP in general, so I am sure this is a rather trivial problem to solve.</div><div><br></div><div>Anyone got any solutions or ideas to point me in the right direction?</div>

<div><br></div><div>Thanks in advance,</div><div><br></div><div>Per</div>