def num_columns(classification, df_group):
    """
    Get the columns number to plot.

    :param classification: (str) classification
    :param df_group: grouped dataframe.
    :return: number of columns to plot
    """
    if classification is None:
        return 2
    if df_group is None and classification is not None:
        return 4
    else:
        return 5
