A scatter of noisy input–output dots from a hidden rule. Choose how many dots, a window radius r, and an input x₀. The dots whose inputs fall within r of x₀ are highlighted and their outputs averaged; that average is the estimate of the rule at x₀. A toggle traces the estimate at every input, and another reveals the hidden rule for comparison. Readouts show the neighbor count, the estimate, the rule's value, and the traced estimate's average squared gap from the rule. A tiny window leaves few or no neighbors and a jagged trace; a huge window blurs the rule's bends.
No dot lands exactly on x₀. So take every dot within r of it and average their y’s.