web-Amazon

一准备实验数据

1.1.下载数据

wget http://snap.stanford.edu/data/amazon/all.txt.gz

1.2.数据分析

1.2.1.数据格式

product/productId: B00006HAXW
product/title: Rock Rhythm & Doo Wop: Greatest Early Rock
product/price: unknown
review/userId: A1RSDE90N6RSZF
review/profileName: Joseph M. Kotow
review/helpfulness: 9/9
review/score: 5.0
review/time: 1042502400
review/summary: Pittsburgh - Home of the OLDIES
review/text: I have all of the doo wop DVD's and this one is as good or better than the
1st ones. Remember once these performers are gone, we'll never get to see them again.
Rhino did an excellent job and if you like or love doo wop and Rock n Roll you'll LOVE
this DVD !!

而，

product/productId: asin, e.g. amazon.com/dp/B00006HAXW #亚马逊标准识别号码（英语：Amazon Standard Identification Number），简称ASIN（productId），是一个由十个字符（字母或数字）组成的唯一识别号码。由亚马逊及其伙伴分配，并用于亚马逊上的产品标识。
product/title: title of the product
product/price: price of the product
review/userId: id of the user, e.g. A1RSDE90N6RSZF
review/profileName: name of the user
review/helpfulness: fraction of users who found the review helpful
review/score: rating of the product
review/time: time of the review (unix time)
review/summary: review summary
review/text: text of the review

1.2.2.数据格式转换

首先，我们需要把原始数据格式转换成dictionary

import pandas as pd
import numpy as np
import datetime
import gzip
import json
from  sklearn.decomposition import PCA
from myria import *
import simplejson

def parse(filename):
    f = gzip.open(filename, 'r')
    entry = {}
    for l in f:
        l = l.strip()
        colonPos = l.find(':')
        if colonPos == -1:
            yield entry
            entry = {}
            continue
        eName = l[:colonPos]
        rest = l[colonPos+2:]
        entry[eName] = rest
    yield entry
    

f = gzip.open('somefile.gz', 'w')
#review_data = parse('kcore_5.json.gz')    
for e in parse("kcore_5.json.gz"):
        f.write(str(e))
f.close()

py文件执行时报错： string indices must be intergers

分析原因：

在.py文件中写的data={"a":"123","b":"456"}，data类型为dict

而在.py文件中通过data= arcpy.GetParameter(0) 获取在GP中传过来的参数{"a":"123","b":"456"}，data类型为字符串！！！

所以在后续的.py中用到的data['a']就会报如上错误！！！

解决方案：

data= arcpy.GetParameter(0)

data=json.loads(data) //将字符串转成json格式

或

data=eval(data) #本程序中我们采用eval（）的方式，将字符串转成dict格式

二.数据预处理

思路：

#import libraries

# Helper functions

# Prepare the review data for training and testing the algorithms

# Preprocess product data for Content-based Recommender System

# Upload the data to the MySQL Database on an Amazon Web Services ( AWS) EC2 instance

2.1创建DataFrame

f parse(path):
  f = gzip.open(path, 'r')
  for l in f:
    yield eval(l)

review_data = parse('/kcore_5.json.gz')
productID = []
userID = []
score = []
reviewTime = []
rowCount = 0

while True:
    try:
        entry = next(review_data)
        productID.append(entry['asin'])
        userID.append(entry['reviewerID'])
        score.append(entry['overall'])
        reviewTime.append(entry['reviewTime'])
        rowCount += 1
        if rowCount % 1000000 == 0:
            print 'Already read %s observations' % rowCount
    except StopIteration, e:
        print 'Read %s observations in total' % rowCount
        entry_list = pd.DataFrame({'productID': productID,
                                   'userID': userID,
                                   'score': score,
                                   'reviewTime': reviewTime})
        filename = 'review_data.csv'
        entry_list.to_csv(filename, index=False)
        print 'Save the data in the file %s' % filename
        break

entry_list = pd.read_csv('review_data.csv')

2.2数据过滤

def filterReviewsByField(reviews, field, minNumReviews):
    reviewsCountByField = reviews.groupby(field).size()
    fieldIDWithNumReviewsPlus = reviewsCountByField[reviewsCountByField >= minNumReviews].index
    #print 'The number of qualified %s: ' % field, fieldIDWithNumReviewsPlus.shape[0]
    if len(fieldIDWithNumReviewsPlus) == 0:
        print 'The filtered reviews have become empty'
        return None
    else:
        return reviews[reviews[field].isin(fieldIDWithNumReviewsPlus)]

def checkField(reviews, field, minNumReviews):
    return np.mean(reviews.groupby(field).size() >= minNumReviews) == 1

def filterReviews(reviews, minItemNumReviews, minUserNumReviews):
    filteredReviews = filterReviewsByField(reviews, 'productID', minItemNumReviews)
    if filteredReviews is None:
        return None
    if checkField(filteredReviews, 'userID', minUserNumReviews):
        return filteredReviews
    
    filteredReviews = filterReviewsByField(filteredReviews, 'userID', minUserNumReviews)
    if filteredReviews is None:
        return None
    if checkField(filteredReviews, 'productID', minItemNumReviews):
        return filteredReviews
    else:
        return filterReviews(filteredReviews, minItemNumReviews, minUserNumReviews)
        
def filteredReviewsInfo(reviews, minItemNumReviews, minUserNumReviews):    
    t1 = datetime.datetime.now()
    filteredReviews = filterReviews(reviews, minItemNumReviews, minUserNumReviews)
    print 'Mininum num of reviews in each item: ', minItemNumReviews
    print 'Mininum num of reviews in each user: ', minUserNumReviews
    print 'Dimension of filteredReviews: ', filteredReviews.shape if filteredReviews is not None else '(0, 4)'
    print 'Num of unique Users: ', filteredReviews['userID'].unique().shape[0]
    print 'Num of unique Product: ', filteredReviews['productID'].unique().shape[0]
    t2 = datetime.datetime.now()
    print 'Time elapsed: ', t2 - t1
    return filteredReviews

allReviewData = filteredReviewsInfo(entry_list, 100, 10)
smallReviewData = filteredReviewsInfo(allReviewData, 150, 15)

理论知识

1. Combining predictions for accurate recommender systems

So, for practical applications we recommend to use a neural network in combination with bagging due to the fast prediction speed.

Collaborative ltering（协同过滤，筛选相似的推荐）：电子商务推荐系统的主要算法，利用某兴趣相投、拥有共同经验之群体的喜好来推荐用户感兴趣的信息