ค้นหาจำนวนผู้เข้าชมที่ไม่ได้เยี่ยมชมพิพิธภัณฑ์ใดๆ ที่เปิดหลังปี 2010
Find the number of visitors who did not visit any museum opened after 2010.
df_museum = pd.DataFrame(columns=['Museum_ID', 'open_year']); df_visitor = pd.DataFrame(columns=['id']); df_visit = pd.DataFrame(columns=['visitor_id', 'Museum_ID'])
df_visitor.loc[~df_visitor['id'].isin(df_visit[df_visit['Museum_ID'].isin(df_museum[df_museum['open_year'] > 2010]['Museum_ID'])]['visitor_id'])].count()