รถยนต์ที่ผลิตในอเมริกามีกี่รุ่น?
How many car models are produced in the usa?
df_CAR_MAKERS = pd.DataFrame(columns=['Id', 'Country']); df_COUNTRIES = pd.DataFrame(columns=['CountryId', 'CountryName']); df_MODEL_LIST = pd.DataFrame(columns=['Maker'])
df_MODEL_LIST[df_MODEL_LIST['Maker'].isin(df_CAR_MAKERS[df_CAR_MAKERS['Country'].isin(df_COUNTRIES[df_COUNTRIES['CountryName'] =='usa']['CountryId'])]['Id'])].shape[0]