Features normalization

features_normalization.py

def normalize_features(df):
    """
    Normalize the features in the data set.
    
    Returns the normalized values, mean and standard deviation for each feature
    """
    mu = df.mean()
    sigma = df.std()
    
    if (sigma == 0).any():
        raise Exception("One or more features had the same value for all samples, so could not be normalized. Please do not include features with only a single value in your model")
    df_normalized = (df - df.mean()) / df.std()
    return df_normalized, mu, sigma