1. Jobin Wilson
jobin.wilson@flytxt.com
Copyright © 2011 Flytxt B.V. All rights reserved. 9/13/2011

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. Session Agenda!
• Recommendation Engines – What's the big deal?
• Conceptual Overview
• Collaborative Filtering
• Engineering Challenges
• Apache Mahout
• Getting your recommender to production
• Q&A
3

4. What's the big deal?

5. Ooh Ads too!

6. Big deal? Advertisers
Recommend Best Ads
Ads
Content
Users
Ad
Network
Content Publishers
ML Algorithms
User Behavior Modelling
Maximization Criteria

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. 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. 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. 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. 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. 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. 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. 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)
mahout-dev-subscribe@apache.org

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. 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. Some more concepts.…
Concept of similarity – distance measure etc
Pearson Correlation
User neighborhood computation

18. THANK YOU
Contact : jobin.wilson@flytxt.com
http://www.flytxt.com/community/
Copyright © 2011 Flytxt B.V. All rights reserved. 9/13/2011 18

19. http://www.flytxt.com/community/
Copyright © 2011 Flytxt B.V. All rights reserved. 9/13/2011 19