Problems executing preprocess_features(features) in train.py

Hi, I´m having problems executing the function preprocess_features(features) in train.py.

def preprocess_features(features): """Row-normalize feature matrix and convert to tuple representation""" rowsum = np.array(features.sum(1)) # <<<--- ERROR r_inv = np.power(rowsum, -1).flatten() r_inv[np.isinf(r_inv)] = 0. r_mat_inv = sp.diags(r_inv) features = r_mat_inv.dot(features) return sparse_to_tuple(features)

The error is: 'tuple' object has no attribute 'sum'

Could somebody help me in solving this issue?

Thank you