import pandas as pd import numpy as np # 1.读取数据 items = pd.read_csv('items.csv', encoding='utf8') signup = pd.read_csv('signup.csv', encoding='utf8') # 2. 合并表 data = pd.merge(left=items, right=signup, on='item_id', how='outer') # 3. 保留数据 data = data[['item_name', 'item_id']] # 4. 分组 data = dat...