def normalize(data, train_split):
    """ Get the standard score of the data.

    :param data: data set
    :param train_split: number of training samples
    :return: normalized data, mean, std
    """
    mean = data[:train_split].mean(axis=0)
    std = data[:train_split].std(axis=0)

    return (data - mean) / std, mean, std