enhancing discovery with solr and mahout

1 CONFIDENTIAL |

Thinking Lucene Think Lucid

Grant IngersollChief ScientistLucid Imagination

Enhancing Discovery with Solr and Mahout

2 CONFIDENTIAL |Copyright Lucid ImaginationCopyright Lucid Imagination

Evolution

Documents•Models•Feature Selection

User Interaction•Clicks•Ratings/Reviews•Learning to Rank•Social Graph

Queries•Phrases•NLP

Content Relationships•Page Rank, etc.•Organization


Minding the Intersection

Search

DiscoveryAnalytics


Background– Apache Mahout– Apache Solr and Lucene

Recommendations with Mahout– Collaborative Filtering

Discovery with Solr and Mahout

Discussion

Topics


Apache Lucene in a Nutshell

http://lucene.apache.org/java Java based Application Programming Interface (API) for adding search and

indexing functionality to applications Fast and efficient scoring and indexing algorithms Lots of contributions to make common tasks easier:

– Highlighting, spatial, Query Parsers, Benchmarking tools, etc.

Most widely deployed search library on the planet

http://lucene.apache.org/java


Apache Solr in a Nutshell

http://lucene.apache.org/solr Lucene-based Search Server + other features and functionality Access Lucene over HTTP:

– Java, XML, Ruby, Python, .NET, JSON, PHP, etc.

Most programming tasks in Lucene are taken care of in Solr Faceting (guided navigation, filters, etc.) Replication and distributed search support Lucene Best Practices


Apache Mahout in a Nutshell

An Apache Software Foundation project to create scalable machine learning libraries under the Apache Software License– http://mahout.apache.org

The Three C’s:– Collaborative Filtering (recommenders)– Clustering– Classification

Others:– Frequent Item Mining– Primitive collections– Math stuff

http://dictionary.reference.com/browse/mahout

http://mahout.apache.org/

http://dictionary.reference.com/browse/mahout

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Recommendations with Mahout


Collaborative Filtering (CF)– Provide recommendations solely based on preferences expressed between

users and items– “People who watched this also watched that”

Content-based Recommendations (CBR)– Provide recommendations based on the attributes of the items and user profile– ‘Modern Family’ is a sitcom, Bob likes sitcoms

• => Suggest Modern Family to Bob

Mahout geared towards CF, can be extended to do CBR– Classification can also be used for CBR

Aside: search engines can also solve these problems

Recommenders


Dracula Jane Eyre Frankenstein Java Programming

Bob 1 4 ??? -

Mary 5 1 4 -

In many instances, user’s don’t provide actual ratings– Clicks, views, etc.

Non-Boolean ratings can also often introduce unnecessary noise– Even a low rating often has a positive correlation with highly rated items in the

real world

Example: Should we recommend Frankenstein to Bob?

To Rate or Not?

Dracula Jane Eyre Frankenstein

Bob 1 4 ???

Mary 5 1 4


Collaborative Filtering with Mahout

Extensive framework for collaborative filtering

Recommenders– User based– Item based– Slope One

Online and Offline support– Offline can utilize Hadoop

Item 1

Item 2

… Item m

User 1 - 0.5 0.9

User 2 0.1 0.3 -

…

User n 0.8 0.7 0.1

Recommendations for User X


User Similarity

Item 1 Item 2 Item 3 Item 4

User 1

User 2 User

3 User 4

What should we recommend for User 1?


Item Similarity

Item 1 Item 2 Item 3 Item 4

User 1

User 2 User

3 User 4

What should we recommend for User 1?


Intuition: There is a linear relationship between rated items– Y = mX + b where m = 1

Solve for b upfront based on existing ratings: b = (Y-X)– Find the average difference in preference value for every pair of items

Online can be very fast, but requires up front computation and memory

Slope One

User Item 1 Item 2

A 3.5 2

B ? 3

User A: 3.5 – 2 = 1.5

Item 1 (User B) = 3 + 1.5 = 4.5


Online– Predates Hadoop– Designed to run on a single node

• Matrix size of ~ 100M interactions– API for integrating with your application

Offline– Hadoop based– Designed to run on large cluster– Several approaches:

• RecommenderJob, ItemSimilarityJob, ParallelALSFactorizationJob

Online and Offline Recommendations


Essentially does matrix multiplication using distributed techniques $MAHOUT_HOME/bin/examples/asf-email-examples.sh

RecommenderJob

101 102 103 104 105

101 7 2 0 1 3

102 2 8 3 5 2

103 0 3 3 6 4

104 1 5 6 4 7

105 3 2 4 7 9

User A

3.0

0

4.0

3.0

2.0

X =

Recs

30

37

38

53

64

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Discovery with Solr


Goals:– Guide users to results without having to guess at keywords– Encourage serendipity– Never show empty results

Out of the Box:– Faceting– Spell Checking– More Like This– Clustering (Carrot2)

Extend– Clustering (with Mahout)– Frequent Item Mining (with Mahout)

Discovery with Solr


Automatically group similar content together to aid users in discovering related items and/or avoiding repetitive content

Solr has search result clustering– Pluggable– Default implementation uses Carrot2

Mahout has Hadoop based large scale clustering– K-Means, Minhash, Dirichlet, Canopy, Spectral, etc.

Clustering


Discovery In Action

Pre-reqs:– Apache Ant 1.7.x, Subversion (SVN)

Command Line 1:– svn co https://svn.apache.org/repos/asf/lucene/dev/trunk solr-trunk– cd solr-trunk/solr/– ant example– cd example– java –Dsolr.clustering.enabled=true –jar start.jar

Command Line 2– cd exampledocs; java –jar post.jar *.xml

http://localhost:8983/solr/browse?q=&debugQuery=true&annotateBrowse=true

https://svn.apache.org/repos/asf/lucene/dev/trunk



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Solr + Mahout


Most Mahout tasks are offline Solr provides many touch points for integration:

– ClusteringEngine• Clustering results

– SearchComponent• Suggestions – Related searches, clusters, MLT, spellchecking

– UpdateProcessor• Classification of documents

– FunctionQuery

Basics


Discover frequently co-occurring items

Use Case: Related Searches from Solr Logs

Hadoop and sequential versions– Parallel FP Growth

Input:– <optional document id>TAB<TOKEN1>SPACE<TOKEN2>SPACE– Comma, pipe also allowed as delimiters

Example: Frequent Itemset Mining


Goal: – Extract user queries from Solr logs– Feed into FIM to generate Related Keyword Searches

Context:– Solr Query logs– bin/mahout regexconverter –input $PATH_TO_LOGS --output /tmp/solr/output

--regex "(?<=(\?|&)q=).*?(?=&|$)" --overwrite --transformerClass url --formatterClass fpg

– bin/mahout fpg --input /tmp/solr/output/ -o /tmp/solr/fim/output -k 25 -s 2 --method mapreduce

– bin/mahout seqdumper --seqFile /tmp/solr2/results/frequentpatterns/part-r-00000

FIM on Solr Query Logs


Key: Chris: Value: ([Chris, Hostetter],870), ([Chris],870), ([Search, Faceted, Chris, Hostetter, Webcast, Power, Mastering],18), ([Search, Faceted, Chris, Hostetter, Webcast, Power],18), ([Search, Faceted, Chris, Hostetter],18), ([Solr, new, Chris, Hostetter, webcast, along, sponsors, DZone, QA, Refcard],12), ([Solr, new, Chris, Hostetter, webcast, along, sponsors, DZone],12), ([Solr, new, Chris, Hostetter, webcast, along, sponsors],12), ([Solr, new, Chris, Hostetter, webcast, along],12), ([Solr, new, Chris, Hostetter, webcast],12), ([Solr, new, Chris, Hostetter],12)

Output


http://lucene.apache.org http://mahout.apache.org http://manning.com/owen http://manning.com/ingersoll

http://www.lucidimagination.com [email protected] @gsingers

Resources

http://lucene.apache.org/

http://mahout.apache.org/

http://manning.com/owen

http://manning.com/ingersoll

mailto:[email protected]

mailto:[email protected]

27 CONFIDENTIAL |


Appendix


Mahout Overview

MathVectors/Matrices/SVD

RecommendersClusteringClassificationFreq. PatternMining

Genetic

Utilities/IntegrationLucene/Vectorizer

Collections (primitives)

Apache Hadoop

Applications

Examples

See http://cwiki.apache.org/confluence/display/MAHOUT/Algorithms

enhancing discovery with solr and mahout

Documents

confidential thinking

lucene recommendations

functionalityaccess

search discovery

search engines

search applications

these5apache solr

deployed search library