มีกี่คนที่ไม่ใช่นักเพาะกาย?
How many persons are not body builders?
df1 = pd.DataFrame(columns=['people_id', 'People_ID']); df2 = pd.DataFrame(columns=['people_id', 'People_ID'])
df2[~df2['people_id'].isin(df1['People_ID'])].shape[0]