standardizing.py

from sklearn.preprocessing import StandardScaler

scaler = StandardScaler(with_mean=True, with_std=True)
# We use the TRAIN set ONLY to fit the scaler
scaler.fit(x_train)

# Now we can use the already fit scaler to TRANSFORM
# both TRAIN and VALIDATION sets
scaled_x_train = scaler.transform(x_train)
scaled_x_val = scaler.transform(x_val)