พิพิธภัณฑ์ที่ยังไม่มีผู้เยี่ยมชมชื่ออะไร?
What is the name of the museum that had no visitor yet?
df_visit = pd.DataFrame(columns=['name', 'Museum_ID', 'museum_id']); df_museum = pd.DataFrame(columns=['name', 'Museum_ID', 'museum_id'])
df_museum.loc[~df_museum['Museum_ID'].isin(df_visit['museum_id']), 'name']