18_UnsupervisedLearing - 11/23/2009 1 Unsupervised learning...

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Unformatted text preview: 11/23/2009 1 Unsupervised learning White dwarfs in the globular cluster M4. In this picture, only the faintest stars are white dwarfs (Credit: NASA and H. Richer (University of British Columbia)) Music Groups X 2 How many clusters are you seeing? A=1 B=2 C=3 D=4 E=Whatever X 1 11/23/2009 2 K ‐ Means • Initialize k cluster centers – Randomly or uniformly • Repeat – Assign datapoints to closest center – Adjust center to mean of all assigned datapoints • Until no change in assignments – Possible cycles? Wikipedia http://www.itee.uq.edu.au/~comp4702/lectures/k ‐ means_bis_1.jpg 11/23/2009 3 www.optimaldesign.com/.../AMAlgorithms.html Learning a mixture of Gaussians 1. Assume there are k components (Gaussians ) generating the data 2. Estimate p ij – the probability point x j was generated by component i. Define 3 Maximize probabilities of components generating their 3. Maximize probabilities of components generating their own data 4. Repeat from 2 until little or no change4....
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This note was uploaded on 05/30/2010 for the course CS 4700 taught by Professor Joachims during the Fall '07 term at Cornell University (Engineering School).

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18_UnsupervisedLearing - 11/23/2009 1 Unsupervised learning...

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