Permute sparse matrix in Python using scipy COO format

permute_sparse_matrix.py

from scipy import sparse

def permute_sparse_matrix(M, row_order=None, col_order=None):
    """
    Reorders the rows and/or columns in a scipy sparse matrix to the specified order.
    """
    if row_order is None and col_order is None:
        return M
    
    new_M = M
    if row_order is not None:
        I = sparse.eye(M.shape[0]).tocoo()
        I.row = I.row[row_order]
        new_M = I.dot(new_M)
    if col_order is not None:
        I = sparse.eye(M.shape[1]).tocoo()
        I.col = I.col[col_order]
        new_M = new_M.dot(I)
    return new_M