Data Analysis with R, Second Edition - Second Edition

The crescent decision boundary

This third dataset, depicted in the bottom-left panel of Figure 10.11, exhibits a very non-linear classification pattern:

Figure 10.14: A plot of the decision boundaries of our four classifiers on our third contrived dataset

In the preceding figure, our top performers are k-NN, which is highly effective with non-linear boundaries, and random forest, which is similarly effective. The decision tree is a little too jagged to compete at the top level. But the real loser here is logistic regression. Because logistic regression returns linear decision boundaries, it is ineffective at classifying the data.

To be fair, ...