题解 | #统计运动会项目报名人数#

import pandas as pd 
import numpy as np 

# 1. 读取数据
items = pd.read_csv('items.csv', encoding='utf8')
singnup = pd.read_csv('signup.csv', encoding='utf8')

# 2. 合并两张表，求运动会报名人数
data = pd.merge(left=items, right=singnup, on='item_id', how='inner')

# 3. 筛选数据
data = data[['item_name', 'item_id']]
# 4. 按项目分组，求报名人数
data = data.groupby(by=['item_name'])['item_id'].count()
print(data)