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← 06-01 Unsupervised Learning

Unit 6 1 Unsupervised Learning

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Showing Revision 1 created 11/28/2012 by Amara Bot.

  1. [Narrator] So welcome to the class
  2. on unsupervised learning.
  3. We talked a lot about supervised learning
  4. in which we are given data and target labels.
  5. In unsupervised learning we're just given data.
  6. So here's a data matrix of
  7. data items of N features each.
  8. There's M and total.
  9. So the task of unsupervised learning is
  10. to find structure in data of this type.
  11. To illustrate why this is an interesting problem
  12. let me start with a quiz.
  13. Suppose we have 2 feature values.
  14. One over here, and one over here,
  15. and our data looks as follows.
  16. Even though we haven't been told about
  17. anything in unsupervised learning, I'd like to
  18. quiz your intuition on the following 2 questions:
  19. 1. Is there structure?
  20. Or put differently do you think there's
  21. something to be learned about data like this,
  22. or is it entirely random?
  23. And second, to narrow this down,
  24. it feels that there are clusters
  25. of data the way I do it.
  26. So how many clusters can you see?
  27. And I give you a couple of choices, 1, 2, 3, 4, or none.