How to apply pca() [Matlab] on high dimensional data
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Atinesh Singh
le 14 Août 2016
Commenté : Akash Reddy
le 10 Nov 2020
I want to apply `pca()` function in `matlab` on data with `500 dimensions`. But pca() has a limit of only 99 dimensions. Do I have to write code for pca.
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the cyclist
le 14 Août 2016
Why do you believe pca has such a limit?
p = pca(rand(1000,700));
runs just fine.
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the cyclist
le 17 Août 2016
I think I finally appreciate what you are missing.
You have more dimensions (p=700) than you have observations (n=100). When p>n, you can fully explain all the variation in the observations with n-1 principal components, which in your case is 99.
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John D'Errico
le 14 Août 2016
Modifié(e) : John D'Errico
le 14 Août 2016
I think the problem is you don't understand the PCA code, at least how to use the tool as provided. READ THE HELP! A problem with size 100x700 for the PCA function is a problem with 700 dimensions, not 100. PCA treats each ROW of the array as one sample, one observation.
Your question (coupled with your later comment) strongly implies that your array is simply transposed from what you need to pass into the PCA tool. Read the help for PCA.
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Walter Roberson
le 16 Août 2016
It is not clear to me why you think that pca has a limit of 99 dimensions?
I had no problem at all a moment ago running pca on a 1000 x 1000 matrix.
Taimour Hamayoun
le 25 Oct 2017
hello! i am new in matlab and i am try to apply PCA on my dataset of 19 dimensions and try to reduce it in 4 dimension but i didnt find the proper way plz guide and provide me a proper source with explanation thanx
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the cyclist
le 27 Oct 2017
May I suggest that you carefully read the documentation and this answer of mine, to get a better understanding of the syntax and output of pca?
Also, you posted this as an answer to a question. It would have garnered more attention as a new question, but I happened to see it.
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