def set_admissions_age_gps(df):
    """
    create admissions data by age_groups
    :param df: DataFrame - expects cleaned 'daily new admissions' data
    :return: DataFrames - rows are dates, columns are age_groups
    """
    # admissions already essentially in the right age groups - just need to combine the 2 youngest age groups
    df['0-17 yrs'] = df['0_to_5'] + df['6_to_17']

    # rename columns for consistency and drop unnecessary ones
    col_name_map = {'18_to_64' : '18-64 yrs',
                    '65_to_84' : '65-84 yrs',
                    '85+' : '85+ yrs'}
    df.rename(columns=col_name_map, inplace=True)
    cols_to_drop = ['0_to_5', '6_to_17']
    df.drop(cols_to_drop, axis=1, inplace=True)

    return df