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Ensemble heterogeneous models . COMP 4332 Tutorial 4 Mar 1 Yin Zhu yinz@cse.ust.hk. Ensemble techniques for heterogeneous classifiers. Greedy search/ensemble selection Stacking More: Sam Reid, A Review of Heterogeneous Ensemble Methods , 2007. . Ensemble iff accurate & diverse .
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Ensemble heterogeneous models COMP 4332 Tutorial 4 Mar 1 Yin Zhu yinz@cse.ust.hk
Ensemble techniques for heterogeneous classifiers • Greedy search/ensemble selection • Stacking • More: • Sam Reid, A Review of Heterogeneous EnsembleMethods, 2007.
Ensemble selection • Caruanaet. al
Three variants to avoid over-fitting • Selection with replacement • Sorted ensemble initialization • Bagged ensemble selection
Good f()? • Many (good) classifiers are fine for f(). • Particularly, Gradient Boosted Trees: • Software: • R’s gbm (tree-based functional gradient descent boosting) • RT-Rank in C++. • TreeNet by Salford Systems. (commercial software) • Used by: • KDDCUP 2009, Winners slow track: University of Melbourne. • 2nd place of Netflix challenge, the Ensemble team, link • Reference: • Friedman, Greedy function approximation: a gradient boosting machine, 1999.
Reference on ensemble in general • Tom Dietterich. • Ensemble Methods in Machine Learning, 2000. PS file. • An Experimental Comparison of Three Methods for Constructing Ensembles of Decision Trees: Bagging, Boosting, and Randomization, 2000. Springer Link. • Leo Breiman, Bagging predictors. 1996. Springer Link. • Freund & Schapire, Experiments with a New Boosting Algorithm. 1996. PDF. • Z.-H. Zhou. Ensemble Methods: Foundations and Algorithms, Boca Raton, FL: Chapman & Hall/CRC, 2012. (ISBN 978-1-439-830031) [TOC; Sample chapters: Chapter 2, Chaper 6]