แต่ละสนามจัดการแข่งขันกี่เกม?
How many games has each stadium held?
df1 = pd.DataFrame(columns=['id']); df2 = pd.DataFrame(columns=['stadium_id'])
df2['stadium_id'].value_counts().to_frame(name='games_count').merge(df1, left_index=True, right_on='id')