แสดงชื่อร้านค้าที่มีอุปกรณ์ในสต็อกมากกว่าหนึ่งประเภท
Show names of shops that have more than one kind of device in stock.
shop_df = pd.DataFrame(columns=['Shop_Name', 'Shop_ID']); stock_df = pd.DataFrame(columns=['Shop_ID'])
stock_df['Shop_ID'].value_counts()[stock_df['Shop_ID'].value_counts() > 1].index.map(lambda id: shop_df.loc[shop_df['Shop_ID']==id, 'Shop_Name'].values[0])