离线召回与排序介绍
3.3 离线召回与排序介绍
学习目标
- 目标
- 了解召回排序作用
- 知道头条推荐召回排序设计
- 应用
- 无
3.3.1 召回与排序介绍
召回：从海量文章数据中得到若干候选文章召回集合(数量较多)
排序：从召回集合中读取推荐文章，构建样本特征进行排序过滤筛选
3.3.1.1项目召回与排序业务流程
3.3.2项目推荐的召回排序设计
-
匿名用户：
- 通常使用用户冷启动方案，区别在于user_id为匿名用户手机识别号(项目不允许匿名用户)
-
所有只正针对于登录用户：
-
用户冷启动（前期点击行为较少情况）
- 非个性化推荐
- 热门召回：自定义热门规则，根据当前时间段热点定期更新维护人点文章库
- 新文章召回：为了提高新文章的曝光率，建立新文章库，进行推荐
- 个性化推荐：
- 基于内容的协同过滤在线召回：基于用户实时兴趣画像相似的召回结果用于首页的个性化推荐
- 非个性化推荐
- 后期离线部分（用户点击行为较多，用户画像完善）
- 建立用户长期兴趣画像（详细）：包括用户各个维度的兴趣特征
- 训练排序模型
- LR模型、FTRL、Wide&Deep
- 离线部分的召回：
- 基于模型协同过滤推荐离线召回：ALS
- 基于内容的离线召回：或者称基于用户画像的召回
3.4 召回表设计与模型召回
学习目标
- 目标
- 知道ALS模型推荐API使用
- 知道StringIndexer的使用
- 应用
- 应用spark完成离线用户基于模型的协同过滤推荐
3.4.1 召回表设计
我们的召回方式有很多种，多路召回结果存储模型召回与内容召回的结果需要进行相应频道推荐合并。
- 方案：基于模型与基于内容的召回结果存入同一张表，避免多张表进行读取处理
- 由于HBASE有多个版本数据功能存在的支持
- TTL=>7776000, VERSIONS=>999999
create 'cb_recall', {NAME=>'als', TTL=>7776000, VERSIONS=>999999}
alter 'cb_recall', {NAME=>'content', TTL=>7776000, VERSIONS=>999999}
alter 'cb_recall', {NAME=>'online', TTL=>7776000, VERSIONS=>999999}
# 例子：
put 'cb_recall', 'recall:user:5', 'als:1',[45,3,5,10]
put 'cb_recall', 'recall:user:5', 'als:1',[289,11,65,52,109,8]
put 'cb_recall', 'recall:user:5', 'als:2',[1,2,3,4,5,6,7,8,9,10]
put 'cb_recall', 'recall:user:2', 'content:1',[45,3,5,10,289,11,65,52,109,8]
put 'cb_recall', 'recall:user:2', 'content:2',[1,2,3,4,5,6,7,8,9,10]
hbase(main):084:0> desc 'cb_recall'
Table cb_recall is ENABLED
cb_recall
COLUMN FAMILIES DESCRIPTION
{NAME => 'als', VERSIONS => '999999', EVICT_BLOCKS_ON_CLOSE => 'false', NEW_VERSION_BEHAVIOR => 'false'
, KEEP_DELETED_CELLS => 'FALSE', CACHE_DATA_ON_WRITE => 'false', DATA_BLOCK_ENCODING => 'NONE', TTL =>
'7776000 SECONDS (90 DAYS)', MIN_VERSIONS => '0', REPLICATION_SCOPE => '0', BLOOMFILTER => 'ROW', CACHE
_INDEX_ON_WRITE => 'false', IN_MEMORY => 'false', CACHE_BLOOMS_ON_WRITE => 'false', PREFETCH_BLOCKS_ON_
OPEN => 'false', COMPRESSION => 'NONE', BLOCKCACHE => 'true', BLOCKSIZE => '65536'}
{NAME => 'content', VERSIONS => '999999', EVICT_BLOCKS_ON_CLOSE => 'false', NEW_VERSION_BEHAVIOR => 'fa
lse', KEEP_DELETED_CELLS => 'FALSE', CACHE_DATA_ON_WRITE => 'false', DATA_BLOCK_ENCODING => 'NONE', TTL
=> '7776000 SECONDS (90 DAYS)', MIN_VERSIONS => '0', REPLICATION_SCOPE => '0', BLOOMFILTER => 'ROW', C
ACHE_INDEX_ON_WRITE => 'false', IN_MEMORY => 'false', CACHE_BLOOMS_ON_WRITE => 'false', PREFETCH_BLOCKS
_ON_OPEN => 'false', COMPRESSION => 'NONE', BLOCKCACHE => 'true', BLOCKSIZE => '65536'}
{NAME => 'online', VERSIONS => '999999', EVICT_BLOCKS_ON_CLOSE => 'false', NEW_VERSION_BEHAVIOR => 'fal
se', KEEP_DELETED_CELLS => 'FALSE', CACHE_DATA_ON_WRITE => 'false', DATA_BLOCK_ENCODING => 'NONE', TTL
=> '7776000 SECONDS (90 DAYS)', MIN_VERSIONS => '0', REPLICATION_SCOPE => '0', BLOOMFILTER => 'ROW', CA
CHE_INDEX_ON_WRITE => 'false', IN_MEMORY => 'false', CACHE_BLOOMS_ON_WRITE => 'false', PREFETCH_BLOCKS_
ON_OPEN => 'false', COMPRESSION => 'NONE', BLOCKCACHE => 'true', BLOCKSIZE => '65536'}
3 row(s)
在HIVE用户数据数据库下建立HIVE外部表,若hbase表有修改，则进行HIVE 表删除更新
create external table cb_recall_hbase(
user_id STRING comment "userID",
als map> comment "als recall",
content map> comment "content recall",
online map> comment "online recall")
COMMENT "user recall table"
STORED BY 'org.apache.hadoop.hive.hbase.HBaseStorageHandler'
WITH SERDEPROPERTIES ("hbase.columns.mapping" = ":key,als:,content:,online:")
TBLPROPERTIES ("hbase.table.name" = "cb_recall");
增加一个历史召回结果表
create 'history_recall', {NAME=>'channel', TTL=>7776000, VERSIONS=>999999}
put 'history_recall', 'recall:user:5', 'als:1',[1,2,3]
put 'history_recall', 'recall:user:5', 'als:1',[4,5,6,7]
put 'history_recall', 'recall:user:5', 'als:1',[8,9,10]为什么增加历史召回表？
- 1、直接在存储召回结果部分进行过滤，比之后排序过滤，节省排序时间
- 2、防止Redis缓存没有消耗完，造成重复推荐，从源头进行过滤
3.4.2 基于模型召回集合计算
初始化信息
import os
import sys
# 如果当前代码文件运行测试需要加入修改路径，避免出现后导包问题
BASE_DIR = os.path.dirname(os.path.dirname(os.getcwd()))
sys.path.insert(0, os.path.join(BASE_DIR))
PYSPARK_PYTHON = "/miniconda2/envs/reco_sys/bin/python"
# 当存在多个版本时，不指定很可能会导致出错
os.environ["PYSPARK_PYTHON"] = PYSPARK_PYTHON
os.environ["PYSPARK_DRIVER_PYTHON"] = PYSPARK_PYTHON
from offline import SparkSessionBase
class UpdateRecall(SparkSessionBase):
SPARK_APP_NAME = "updateRecall"
ENABLE_HIVE_SUPPORT = True
def __init__(self):
self.spark = self._create_spark_session()
ur = UpdateRecall()
3.4.2.1 用户日志信息处理
- 目标：处理成ALS模型所需数据类型和格式
- 步骤：
- 数据类型转换,clicked
- 用户ID与文章ID处理
数据类型转换,clicked
ur.spark.sql("use profile")
user_article_click = ur.spark.sql("select * from user_article_basic").\
select(['user_id', 'article_id', 'clicked'])
# 更换类型
def change_types(row):
return row.user_id, row.article_id, int(row.clicked)
user_article_click = user_article_click.rdd.map(change_types).toDF(['user_id', 'article_id', 'clicked'])
用户ID与文章ID处理，编程ID索引
from pyspark.ml.feature import StringIndexer
from pyspark.ml import Pipeline
# 用户和文章ID超过ALS最大整数值，需要使用StringIndexer进行转换
user_id_indexer = StringIndexer(inputCol='user_id', outputCol='als_user_id')
article_id_indexer = StringIndexer(inputCol='article_id', outputCol='als_article_id')
pip = Pipeline(stages=[user_id_indexer, article_id_indexer])
pip_fit = pip.fit(user_article_click)
als_user_article_click = pip_fit.transform(user_article_click)
3.4.2.2 ALS 模型训练与推荐
ALS模型需要输出用户ID列，文章ID列以及点击列
from pyspark.ml.recommendation import ALS
# 模型训练和推荐默认每个用户固定文章个数
als = ALS(userCol='als_user_id', itemCol='als_article_id', ratingCol='clicked', checkpointInterval=1)
model = als.fit(als_user_article_click)
recall_res = model.recommendForAllUsers(100)
3.4.2.3 推荐结果处理
通过StringIndexer变换后的下标知道原来的和用户ID
# recall_res得到需要使用StringIndexer变换后的下标
# 保存原来的下表映射关系
refection_user = als_user_article_click.groupBy(['user_id']).max('als_user_id').withColumnRenamed(
'max(als_user_id)', 'als_user_id')
refection_article = als_user_article_click.groupBy(['article_id']).max('als_article_id').withColumnRenamed(
'max(als_article_id)', 'als_article_id')
# Join推荐结果与 refection_user映射关系表
# +-----------+--------------------+-------------------+
# | als_user_id | recommendations | user_id |
# +-----------+--------------------+-------------------+
# | 8 | [[163, 0.91328144]... | 2 |
# | 0 | [[145, 0.653115], ... | 1106476833370537984 |
recall_res = recall_res.join(refection_user, on=['als_user_id'], how='left').select(
['als_user_id', 'recommendations', 'user_id'])
对推荐文章ID后处理：得到推荐列表,获取推荐列表中的ID索引
# Join推荐结果与 refection_article映射关系表
# +-----------+-------+----------------+
# | als_user_id | user_id | als_article_id |
# +-----------+-------+----------------+
# | 8 | 2 | [163, 0.91328144] |
# | 8 | 2 | [132, 0.91328144] |
import pyspark.sql.functions as F
recall_res = recall_res.withColumn('als_article_id', F.explode('recommendations')).drop('recommendations')
# +-----------+-------+--------------+
# | als_user_id | user_id | als_article_id |
# +-----------+-------+--------------+
# | 8 | 2 | 163 |
# | 8 | 2 | 132 |
def _article_id(row):
return row.als_user_id, row.user_id, row.als_article_id[0]
进行索引对应文章ID获取
als_recall = recall_res.rdd.map(_article_id).toDF(['als_user_id', 'user_id', 'als_article_id'])
als_recall = als_recall.join(refection_article, on=['als_article_id'], how='left').select(
['user_id', 'article_id'])
# 得到每个用户ID 对应推荐文章
# +-------------------+----------+
# | user_id | article_id |
# +-------------------+----------+
# | 1106476833370537984 | 44075 |
# | 1 | 44075 |
获取每个文章对应的频道，推荐给用户时按照频道存储
ur.spark.sql("use toutiao")
news_article_basic = ur.spark.sql("select article_id, channel_id from news_article_basic")
als_recall = als_recall.join(news_article_basic, on=['article_id'], how='left')
als_recall = als_recall.groupBy(['user_id', 'channel_id']).agg(F.collect_list('article_id')).withColumnRenamed(
'collect_list(article_id)', 'article_list')
als_recall = als_recall.dropna()
3.4.2.4 召回结果存储
- 存储位置，选择HBASE
HBASE表设计：
put 'cb_recall', 'recall:user:5', 'als:1',[45,3,5,10,289,11,65,52,109,8]
put 'cb_recall', 'recall:user:5', 'als:2',[1,2,3,4,5,6,7,8,9,10]
存储代码如下：
def save_offline_recall_hbase(partition):
"""离线模型召回结果存储
"""
import happybase
pool = happybase.ConnectionPool(size=10, host='hadoop-master', port=9090)
for row in partition:
with pool.connection() as conn:
# 获取历史看过的该频道文章
history_table = conn.table('history_recall')
# 多个版本
data = history_table.cells('reco:his:{}'.format(row.user_id).encode(),
'channel:{}'.format(row.channel_id).encode())
history = []
if len(data) >= 2:
for l in data[:-1]:
history.extend(eval(l))
else:
history = []
# 过滤reco_article与history
reco_res = list(set(row.article_list) - set(history))
if reco_res:
table = conn.table('cb_recall')
# 默认放在推荐频道
table.put('recall:user:{}'.format(row.user_id).encode(),
{'als:{}'.format(row.channel_id).encode(): str(reco_res).encode()})
conn.close()
# 放入历史推荐过文章
history_table.put("reco:his:{}".format(row.user_id).encode(),
{'channel:{}'.format(row.channel_id): str(reco_res).encode()})
conn.close()
als_recall.foreachPartition(save_offline_recall_hbase)