问嵌套的for循环遍历python列表

EN

    import numpy as np
    import pandas as pd
    import matplotlib.pyplot as plt

    data=pd.read_csv('data.csv',index_col=0, encoding="ISO-8859-1")       

    # Get list of unique items
    itemList=list(set(data["product_ref"].tolist()))

    # Get count of customers
    userCount=len(set(data["customer_id"].tolist()))

    # Create an empty data frame to store item affinity scores for items.
    itemAffinity= pd.DataFrame(columns=('item1', 'item2', 'score'))

    def itemUsers(ind):
      return data[data.product_ref==itemList[ind]]["customer_id"].tolist()

    rowCount=0
    for ind1 in range(len(itemList)): 
        item1Users = itemUsers(ind1) 
        pool = Pool()
        pool.map(loop2, data_inputs)
        for ind2 in range(ind1+1, len(itemList)): 
            print(ind1, ":", ind2)       
            item2Users = itemUsers(ind2) 
            commonUsers= len(set(item1Users).intersection(set(item2Users))) 
            score=commonUsers / userCount
            itemAffinity.loc[rowCount] = [itemList[ind1],itemList[ind2],score] 
            rowCount +=1