RuixueLiu / pmtk3

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fisherDiscrimVowelDemo (pca-part issue?) #62

Open GoogleCodeExporter opened 8 years ago

GoogleCodeExporter commented 8 years ago
What steps will reproduce the problem?

1.Run the fisherDiscrimVowelDemo.m

What is the expected output? What do you see instead?

In the "%PCA projection to 2d" part of the code the function "pcaPmtk" is 
invoked twice: (i) in line 12, for the whole dataset and (ii) in line 17, for 
the class means. 

Wouldn't this correspond to two different projection subspaces? In other words, 
wouldn't B and Bmu span two different linear subspaces? But if this the case, 
shouldn't we avoid plotting the projected points and projected means in the 
same plot (see lines 41-48)?

Would it make more sense to invoke the function "pcaPmtk" only once (for the 
whole dataset as it is done in line 12) and then project the class means to the 
linear subspace spanned by the basis vectors B (already found using pcaPmtk)? 

I would therefore replace line 17:

[Bmu, muC2d] = pcaPmtk(muC, 2); 

with

muC2d = centerCols(muC)*B;

Does this make sense?

Any feedback would be greatly appreciated.

Many thanks

What version / revision of the product are you using? On what operating
system?

pmtk3 / Windows

Please provide any additional information below.

Original issue reported on code.google.com by email.po...@gmail.com on 2 Sep 2013 at 12:47

GoogleCodeExporter commented 8 years ago
Moved to GitHub: https://github.com/probml/pmtk3/issues/62

Original comment by irosen on 4 Jan 2014 at 2:39