How to do your own topic modeling
David Newman
University of California, Irvine
TwTT session
Yale University
Tuesday October 4, 2011
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Acknowledgements
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We gratefully acknowledge support from IMLS
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Topic-modeling-tool is based off of Mallet (UMass)
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Arun Balagopalan developed the topic-modelingtool
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(from Blei)
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(from Blei)
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Topic Modeling Tool
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Simple-to-use graphical user interface for doing
topic modeling
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Simple interface
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csv and html output
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Designed for non-technical users
Openly available at Google Code:
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http://code.google.com/p/topic-modeling-tool/
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Why would you want to topic model?
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Collection management
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Subject metadata enhancement
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Say you are managing a number of collections.
Topic model each collection to describe what is in
that collection
Say you have a collection of heterogeneous text
content, with partial and/or variable subject
tagging. Topic model could provide uniform
subject tags across this collection
Other reasons? (Let's hear from you!)
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Input to Topic Model is Easy
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Input the document collection
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Folder containing collection of .txt files, or
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Single .txt file, one document per line
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(let D denote # of documents in collection)
Input number of topics
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(let T denote number of topics)
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Let's try it
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Download TopicModelingTool.jar
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Select text collection for topic modeling
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(The google code site has sample text collections for
demonstration purposes)
Hit the button!
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Let's look at the output
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file:///home/newman/topic-modeling-tool/economy/try1_
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Output files
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List of T topics
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List of topics in each of D documents
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List of top-ranked documents in each of T topics
Output file formats
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html (view in browser)
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csv (load in Excel)
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What can I control?
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Number of topics, T
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List of stopwords (the, and, ...)
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Whether to preserve case
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Number of words printed per topic (default = 10)
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Threshold for tagging a document with a topic (e.g.
5%, 10%, etc)
Number of iterations
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What can I control?
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Number of topics, T
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T = 10 topics is default
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Suggestions
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for D=1,000-10,000 ... set T = 10-40
for D=10,000-100,000 ... set T = 50-200
for D=100,000-1,000,000 ... set T = 250-1000
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first tried T = 20 topics
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now try T = 40 topics
file:///home/newman/topic-modeling-tool/economy/try2_
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Compare T=20 and T=40 topics
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T=20 topics
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topic-17: bush japan president states united world
china north country korea
T=40 topics
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topic-12: bush president china states chinese people
united friday day nation
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topic-8: japan bush korea north world japanese
united south states economic
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How does it work?
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Topic model assumes documents exhibit multiple topics
Topic model learns from patterns of words that tend to cooccur within documents, e.g. say we see many documents
mentioning these words:
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health, insurance, patient, ...
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health, care, doctor ...
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prescription, drugs ...
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medicare, medicaid, benefit ...
Then might get topic looking like this:
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health care insurance medicare drug medicaid
prescription ...
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(from Blei)
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(from Blei)
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What can I control?
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List of stopwords (the, and, ...)
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What can I control?
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List of stopwords (the, and, ...)
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Oops ... try again ... mystopwords2.txt
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Other things to try
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Preserve case
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Threshold for tagging a document with a topic
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Number of topic words printed
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How long does it take?
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Should take minutes/hours/days depending on size
of topic model
Proportional to:
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Total number of words in collection (or documents in
collection)
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Number of topics, T
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Number of iterations
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What next?
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What do I do with my topic model?
html good for viewing, re-running topic model,
spot-checking
csv good for tagging, subject metadata
enhancement, subject indexing, etc.
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Applications
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National Science Foundation
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National Institutes of Health
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Other
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National Science Foundation
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National Science Foundation
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National Institutes of Health
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National Institutes of Health
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National Institutes of Health
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FAQs
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Can I topic model a single text document?
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How could I topic model a long book?
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Is learning T topics in fact learning the first-T topics (if I
learn 10 topics, then later learn 20 topics, are the first 10 of the
20-topic-model the same as the 10-topic model)?
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What if my topics are too general?
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What if my topics are indistinguishable?
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Do topics have an order?
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How to set topic model parameters (number of iterations)
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Help! It's not working!
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We're here to help, we want to make this a usable
tool
Send help requests to: [email protected]
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