For learners it is confusing to see the nonlinear decision boundaries for linear and logistic regression, IMO a note about the feature expansion should be added
Good point, I've updated my post. For linear and logistic regression there's cubic expansion on the features (which is how they can fit curved problems). The relevant Javascript code is on lines 91 and 96.
PS: It can be changed to "linear" or "quadratic" as well.
