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Manifold sculpting seems to produce wrong results.

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Anonymous
2015-09-08
2015-09-08
  • Anonymous

    Anonymous - 2015-09-08

    I want to implement the example of letter 'A' on the wiki page of nonlinear dimensionality reduction(https://en.wikipedia.org/wiki/Nonlinear_dimensionality_reduction). I use python to generate the data, and then use waffles to do dimensionality reduction. However, the result of PCA is a cicle while the result of manifold sculpting is some disordered points. Could someone help me with this problem?

     
  • Mike Gashler

    Mike Gashler - 2015-09-08

    I did that a long time ago, and have since forgotten some of the details. However I found this in a search of my computer: http://uaf46365.ddns.uark.edu/letter.zip
    It may or may not be the data that produced that figure. The file log.txt appears to contain some notes about the exact commands I used to produce varying quality of results. Apparently, it took some experimentation before I was happy with the results. I am not sure whether the best one is in there or not.

    (Tangentially, if you're looking for an NLDR algorithm that just works in a variety of cases, frankly, I'd recommend looking into some of the neural network-based feature-learning methods. Manifold Sculpting can produce good results in specific cases, but it requires careful tuning and a lot of processing time. Ultimately, all of the NLDR methods that require neighbor-finding as their first step end up being too slow for general applications, too susceptible to problems with poorly-sampled manifolds, and unable to generalize effectively for out-of-band samples. The neural network approaches, by contrast, require no neighbor-finding step, and are designed to generalize.)

     

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