def create_training_validation_df(df_complete_ds, test_fold):
    """
        Divide the data in train and test in a subject-wise 5-CV way. The division is generated before running the training
        of each fold.

        :param df_complete_ds:[DataFrame] Dataframe with the complete list of files generated by create_complete_dataset(..) function
        :param test_fold:[int] Fold to create the train and test sets [ranging from 1 - 5]
    """
    #training
    train_df = df_complete_ds.loc[df_complete_ds["test_fold"] != test_fold]
    #validation or test
    test_df = df_complete_ds.loc[df_complete_ds["test_fold"] == test_fold]
    #drop fold columns:
    train_df = train_df.drop(["test_fold"], axis=1)
    test_df = test_df.drop(["test_fold"], axis=1)
    return train_df, test_df