'Number of stored values, including explicit zeros.
Parameters
axis : None, 0, or 1
Select between the number of values across the whole matrix, in
each column, or in each row.
See also
count_nonzero : Number of non-zero entries'

def getnnz(self, axis=None):

    raise NotImplementedError(('getnnz    not    implemented    for    %s.' % self.__class__.__name__))
