2D kernel classifier: add points and show the boundary in the same panel

Click to add labeled 2D points. After fitting, the same panel shows decision regions and the decision boundary for a kernel classifier of the form f(x)=∑ᵢ αᵢ k(xᵢ,x)+b. You can switch the kernel, the loss (logistic / hinge / squared / absolute on ±1 targets), and the optimizer settings.
class +1    class −1    decision boundary
Suggested use
Load the concentric example and compare:
linear + logistic
poly degree 2 + logistic
RBF + logistic

Then change the loss to hinge / squared / absolute to show how the fitted boundary changes. The γ and λ ranges are intentionally wide so you can show under/over-smoothing.