Monthly Archives: December 2016

Questions on K means method

Posted on December 25, 2016 by faye1010

What is K means algorithm? What is the optimization function? The partial derivative of Distortion J  with respect to each center location must be zero. Will the algorithm stop? When J is minimized, (1) each is encoded by its nearest center … Continue reading →

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SVM notes

Posted on December 24, 2016 by faye1010

Support vector machine can be used for classification and regression. It has successful applications in many fields, like bioinformatics, text, image recognition, etc. Its main ideas are large margin and kernel trick. Margins: 1.Intuition To make things easier, we suppose … Continue reading →

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A brief introduction to Neural Networks with an example in R

Posted on December 17, 2016 by faye1010

Motivation: Suppose there are two predictors and the decision boundary is non-linear, then one can introduce quadratic terms in the logistic regression, i.e. $ latex  h_{\theta}(x)=g(\theta_0+\theta_1 x_1+\theta_3 x_2+\theta_4 x_1^2+\theta_5 x_1x_2+\theta_6 x_2^2),$ where is the logistic function. However, most questions have more … Continue reading →

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