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Author: budaLi

电影推荐/1.py

@@ -0,0 +1,133 @@
+# coding=utf-8
+# Copyright (c) 2020 ichinae.com, Inc. All Rights Reserved
+"""
+Module Summary Here.
+Authors: lijinjun1351@ichinae.com
+"""
+# -*- coding:utf-8 -*-
+"""
+author:david
+data:2018***
+util funcution
+"""
+import os
+
+
+def get_item_info(input_file):
+    '''
+    得到item的信息
+    :param input_file:
+    :return: a dict: key:itemid  value:[title,genre]
+    '''
+    if not os.path.exists(input_file):
+        return {}
+    linenum = 0
+    item_info = {}
+    fp = open(input_file, encoding='utf-8')
+    for line in fp:
+        if linenum == 0:
+            linenum += 1
+            continue
+        item = line.strip().split(',')
+        if len(item) < 3:  # 观察数据集，发现一般由三列组成，但是有些电影title包含逗号，需要分开讨论
+            continue  # 小于3，则直接过滤
+        elif len(item) == 3:
+            itemid, title, genre = item[0], item[1], item[2]
+        elif len(item) > 3:
+            itemid = item[0]
+            genre = item[-1]
+            title = ','.join(item[1:-1])  # 还原包含逗号被误分割的title
+        item_info[itemid] = [title, genre]
+    fp.close()
+    return item_info
+
+
+def get_ave_score(input_file):
+    '''
+    获取item的平均评分
+    :param input_file: user rating file
+    :return:a dict,key:itemid,value:ave_socre
+    '''
+    if not os.path.exists(input_file):
+        return {}
+    linenum = 0
+    record_dict = {}
+    score_dict = {}
+    fp = open(input_file)
+    for line in fp:
+        if linenum == 0:
+            linenum += 1
+            continue
+        item = line.strip().split(',')
+        if len(item) < 4:
+            continue
+        userid, itemid, rating = item[0], item[1], item[2]
+        if itemid not in record_dict:
+            record_dict[itemid] = [0, 0]
+        record_dict[itemid][0] += 1  # 记录出现的次数
+        record_dict[itemid][1] += float(rating)
+    fp.close()
+    for itemid in record_dict:
+        score_dict[itemid] = round(record_dict[itemid][1] / record_dict[itemid][0], 3)  # 精度为3
+    return score_dict
+
+
+def get_train_data(input_file):
+    '''
+    获得训练样本
+    :param input_file:
+    :return: list[user,item,label]
+    '''
+    if not os.path.exists(input_file):
+        return []
+    score_dict = get_ave_score(input_file)
+    # 负采样要保证正负样本均衡
+    pos_dict = {}
+    neg_dict = {}
+    train_data = []
+    score_thr = 4
+    fp = open(input_file)
+    linenum = 0
+    for line in fp:
+        if linenum == 0:
+            linenum += 1
+            continue
+        item = line.strip().split(',')
+        if len(item) < 4:
+            continue
+        userid, itemid, rating = item[0], item[1], float(item[2])
+        if userid not in pos_dict:
+            pos_dict[userid] = []
+        if userid not in neg_dict:
+            neg_dict[userid] = []
+        if rating >= score_thr:  # 大于阙值则看作正样本
+            pos_dict[userid].append((itemid, 1))
+        else:
+            score = score_dict.get(itemid, 0)
+            neg_dict[userid].append((itemid, score))
+    fp.close()
+    for userid in pos_dict:
+        data_num = min(len(pos_dict[userid]), len(neg_dict.get(userid, [])))
+        if data_num > 0:
+            train_data += [(userid, temp[0], temp[1]) for temp in pos_dict[userid]][:data_num]
+        else:
+            continue
+        # 对负样本按照平均评分进行排序，element是[itemid,score]
+        sorted_neg_list = sorted(neg_dict[userid], key=lambda element: element[1], reverse=True)[:data_num]
+        train_data += [(userid, temp[0], 0) for temp in sorted_neg_list]
+    return train_data
+
+
+if __name__ == '__main__':
+    item_dict = get_item_info("movie.txt")
+    print(len(item_dict))
+    print(item_dict["1"])
+    print(item_dict['11'])
+
+    score_dict = get_ave_score("rating.txt")
+    print(len(score_dict))
+    print(score_dict['1'])
+
+    train_data = get_train_data("rating.txt")
+    print(len(train_data))
+