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Recommendation engines matching items to users


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Harnessing Hadoop for Big Data, Series II

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Recommendation engines matching items to users

  1. 1. Jobin Wilson jobin.wilson@flytxt.comCopyright © 2011 Flytxt B.V. All rights reserved. 9/13/2011
  2. 2. Who am I ? • Architect @ Flytxt (Big Data Analytics & Automation) • Passionate about data, distributed computing , machine learning • Previously •Virtualization & Cloud Lifecycle Management(BMC) • Designed and Implemented Cloud Life Cycle Management Interface@BMC • Large Scale Data Centre Automation(AOL) • Implemented Centralized Data Center Management Framework for AOL •Workflow Systems & Automation (Accenture) • Implemented Service Management Suit for various customers
  3. 3. Session Agenda!• Recommendation Engines – Whats the big deal?• Conceptual Overview• Collaborative Filtering• Engineering Challenges• Apache Mahout• Getting your recommender to production• Q&A 3
  4. 4. Whats the big deal?
  5. 5. Ooh Ads too!
  6. 6. Big deal? Advertisers Recommend Best Ads Ads Content Users Ad Network Content Publishers ML Algorithms User Behavior Modelling Maximization Criteria
  7. 7. BTW, What was the challenge?User Base : 2 billion+ users world wideContent Base : 12.51 billion+ indexed pagesAdvertiser Base : millions of active advertisersReal-time nature : Responses in < 200 msMulti –objective optimization problemNoisy Data
  8. 8. Recommendation Engines: Overview A specific type of information filtering system technique that attempts to recommend information items or social elements that are likely to be of interest to the user. Technologies that can help us sift through all the available information to predict products or services that could be interesting to us. Applying knowledge discovery techniques to the problem of making personalized recommendations for information, products or services, usually during a live interaction.
  9. 9. We need a crystal ball to predict ? We all have opinions/tastes which we express as our likes or dislikes. Our tastes follow some patterns. We tend to like things which are similar to things which we already like(e.g. Songs) We tend to like things which are liked by people who are similar to us(e.g. Movies) From fancy research to mainstream
  10. 10. Collaborative Filtering Problem : We have U users and I items in the system, a user Uk need to be recommended with a set of m items which are yet un-picked by him which he might be interested in picking up. Solution : Maintain a database of users’ ratings of a variety of items. For a given user, find other similar users whose ratings strongly correlate with the current user - User Neighborhood Recommend items rated highly by these similar users, but not rated by the current user. E.g. Amazon, Filpkart etc
  11. 11. Utility Matrix Matrix of values representing each user’s level of affinity to each item. Sparse matrix Recommendation engine needs to predict the values for the empty cells based on available cell values Denser the matrix, better the quality of recommendation User | Item i1 i2 i3 i4 i5 u1 r12 r14 r15 u2 r21 r22 r25 u3 r32 r34 u4 r43 r45
  12. 12. Engineering Challenges Massive Data Volume : how do I deal with TBs of raw data to build my recommendations? Hadoop and Map-Reduce shines! How can I make it work in ‘Real-Time’ ? Batch pre-compute and store in HBase could help! Will my solution scale? soon my user base is going to double!. Sure, you can make it scale!
  13. 13. Engineering Challenges Do I need a cloud based infrastructure? Depends! Hadoop compatible Machine Learning library? Mahout would help! How can I represent/transform my input data appropriately? Pig/Hive might help!, if not ,map-reduce is always there!
  14. 14. Apache Mahout Overview Scalable machine learning library core algorithms for clustering, classification and batch based collaborative filtering implemented over Hadoop Few popular algos: K-Means, fuzzy K-Means ,Canopy clustering ,LDA etc Vibrant community support. Used by – Adobe ,Yahoo! ,Amazon , AOL, Flytxt…. (list goes on) 
  15. 15. Taking Recommendation Engines to production Analyzing the input data, what kind of info I can collect from users Selecting the appropriate recommender (e.g. user based, Item based ) Strategy to recommend to anonymous users(or first time users) Strategy for distributed computing, modeling the problem as map- reduce Choosing the deployment model Monitoring the system
  16. 16. Conclusion Very popular field of research and implementation More and more products and services are leveraging the concept From fancy research to live production systems at scale Making peoples lives easier by assisting in making decisions
  17. 17. Some more concepts.… Concept of similarity – distance measure etc Pearson Correlation User neighborhood computation
  18. 18. THANK YOU Contact : jobin.wilson@flytxt.com Copyright © 2011 Flytxt B.V. All rights reserved. 9/13/2011 18
  19. 19. Copyright © 2011 Flytxt B.V. All rights reserved. 9/13/2011 19