Re: [Scikit-learn-general] PCA nipals and Sparse PCA

2014-06-05 Thread Kyle Kastner
I am planning to work on NIPALS after the 0.15 sklearn release - there are several good papers I will try to work with and implement. Simple, high level description: http://www.vias.org/tmdatanaleng/dd_nipals_algo.html Simple MATLAB (will start with this first likely):

Re: [Scikit-learn-general] PCA nipals and Sparse PCA

2014-06-05 Thread Kyle Kastner
Sorry - in my previous email I should have said that I will be working on NIPALS PCA . As you correctly note PLS(algorithm=nipals) is solving the PLS objective, which is different than the PCA objective. For anyone who is curious, see

[Scikit-learn-general] PCA nipals and Sparse PCA

2014-06-04 Thread Luca Puggini
Hi, I was looking to the code in the cross-decomposition section. In PLS the PCs are computed in order to maximize the correlation between X and y and not to maximize the covariance of X. def _nipals_twoblocks_inner_loop(X, Y, mode=A, max_iter=500, tol=1e-06,

[Scikit-learn-general] PCA nipals and Sparse PCA

2014-06-01 Thread Luca Puggini
Hi, Just to summarize the situation and to avoid confusion. There are mainly two things where I was focusing my attention. 1 - Nipals PCA ( http://en.wikipedia.org/wiki/Principal_component_analysis#The_NIPALS_method ) This is a good alternative to SVD and it is much faster in situations where

Re: [Scikit-learn-general] PCA nipals and Sparse PCA

2014-06-01 Thread Gael Varoquaux
On Mon, Jun 02, 2014 at 12:27:34AM +0100, Luca Puggini wrote: This is a good alternative to SVD and it is much faster in situations where we have a lot of variables and we are interested only in a small number of components. This is a well known and tested algorithm and I was actually