python scipy CSR format

gistfile1.py

# Got an answer from the Scipy user group:
# http://stackoverflow.com/questions/8955448/save-load-scipy-sparse-csr-matrix-in-portable-data-format
# A csr_matrix has 3 data attributes that matter: .data, .indices, and .indptr. All are simple ndarrays, so numpy.save will work on them. Save the three arrays with numpy.save or numpy.savez, load them back with numpy.load, and then recreate the sparse matrix object with:

# new_csr = csr_matrix((data, indices, indptr), shape=(M, N))
# So for example:

def save_sparse_csr(filename,array):
    np.savez(filename,data = array.data ,indices=array.indices,
             indptr =array.indptr, shape=array.shape )

def load_sparse_csr(filename):
    loader = np.load(filename)
    return csr_matrix((  loader['data'], loader['indices'], loader['indptr']),
                         shape = loader['shape'])