reverse pandas dummies

reverse_dummies.py

def remove_column_name(value):
    return value[value.rfind('_')+1:]

def check_categorical_column(columns):
    dict_column_name = {}
    for column in columns:
        name = column[:column.rfind('_')]
        dict_column_name.setdefault(name,[]).append(column)
    return dict_column_name

def reverse_dummies(df):
    df_temp = df.copy()
    dict_column_name = check_categorical_column(df_temp)
    for key, value in dict_column_name.items():
        if len(value) > 1:
            dummies = df_temp[value]
            df_temp[key] = pd.Series(dummies.columns[np.where(dummies != 0)[1]])
            df_temp[key] = df_temp[key].apply(remove_column_name)
            df_temp.drop(value, axis=1, inplace=True)
    return df_temp

reverse_dummies(df)