R2D3: Visual explanations of ML principles

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Stephanie and Tony over at R2D3 have made some really nice and intuitive visualizations of how machine learning works. So far they have two parts - part I is an introduction to ML, and part II visualizes one of the fundamental laws of ML, namely, bias-variance tradeoff. In both cases they use decision trees to explain the underlying principles. I highly recommend checking them out: http://www.r2d3.us/