题解 | 多报名表的运动项目人数统计
import pandas as pd
items = pd.read_csv('items.csv')
signup = pd.read_csv('signup.csv')
signup1 = pd.read_csv('signup1.csv')
data_s = pd.concat([signup, signup1], axis=0) # 按行拼接两个表
data = pd.merge(data_s, items, on='item_id', how='inner')
print(data.groupby('item_name')['employee_id'].count())
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