PCA in R
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Added: 11 months ago
From: off2themovies2
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  • thank you. It is very useful

  • This video and your others have been very useful but I have a quick question:

    My data set contains 4 different skull measurements from 2 different epochs. How do I account for the division in the dataset by epoch? I'm thinking that it would involve plotting the observations in colors in the biplot, each epoch being a different color. Is there a way to do that easily in R or am I better off taking it to Sigmaplot?

  • @WolferaTheJackal The predict function should work. Probably the reason you are getting really big values it that you are using the cor=TRUE which centers and scales the data. You would need to center and scale your Xnew data then project it.

    Hope this helps.

  • @WolferaTheJackal Why don't you just use the scores=TRUE statement? That will project it into the space.

    In your code the problem is that you are using *. This isn't matrix multiplication in R. It is elementwise multiplication. Matrix mutliplication is %*%. So you code should look like:

    Tnew <- Xnew%*%P

    That should work.

  • As I don't do a whole lot of work with SVMs from when I have used them I have used the libsvm package. Here is a link to a paper that has examples of using SVMs in a few different packages and an assessment of them. It also gives example code that you can run to get things going.

    Journal of statistical software... version 15, issue 9.

  • I think how support vector machines work in R depends on the SVM package you are using.  Some packages are easier to use than others.

  • The point of these videos is so that you don' t have to buy a book. They are here free. However the fact that you would buy a book from me is very flattering. Feel free to request other topics. I really don't know what people want to learn outside of basic statistical methods.

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  • I love your video, helped me so much~~~you should write a book....and I will buy~haha

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