Gallery of 2-d classification

Through the Machine Learning Newsgroup I was pointed to a gallery of 2D classifiers.

There are a number of strange or simple classifcation problems such as this one:



And Fawcett (the author) has trained a variety of different classifcation algorithms to try and detect the pattern. Most social scientists will be familiar with the logistic regression. You can see on the above example that logistic regression will fail horribly:



Then, one of my recent machine learning interests, support vector machines, does a bit better:



In any of linear cases logistic regression performs fantastic. While some of the other algorithms will get messy or incorrect results using a small N, the logistic will get an almost perfect classification. This page is a great resource for exploring the power and limitations of several classification methods.