> Indeed. In practical terms: when PCA subtracts the columnwise mean of > X both in fit and in transform, it destroys the sparsity, so it's no > good for sets of documents. See also > http://metaoptimize.com/qa/questions/3340/difference-between-lsi-and-pca
OK, that wasn't clear to me. In particular it wasn't clear to me that PCA always substracted means, I thought that it was just one of the many variants. Anyhow, this link should be documented both ways (in the PCA docs, and in the LSI PR). Thanks! ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. SALE $99.99 this month only -- learn more at: http://p.sf.net/sfu/learnmore_122412 _______________________________________________ Scikit-learn-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/scikit-learn-general
