https://stats.stackexchange.com/questions/69157/why-do-we-need-to-normalize-data-before-principal-component-analysis-pca On Thursday, May 24, 2018, 4:41:07 PM PDT, Shiheng Duan <shid...@ucdavis.edu> wrote: Hello all, I wonder is it necessary or correct to do z score transformation before PCA? I didn't see any preprocessing for face image in the example of Faces recognition example using eigenfaces and SVMs, link:http://scikit-learn.org/stable/auto_examples/applications/plot_face_recognition.html#sphx-glr-auto-examples-applications-plot-face-recognition-py I am doing on a similar dataset and got a weird result if I standardized data before PCA. The components figure will have a strong gradient and it doesn't make any sense. Any ideas about the reason? Thanks. _______________________________________________ scikit-learn mailing list scikit-learn@python.org https://mail.python.org/mailman/listinfo/scikit-learn
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