Regression

1 import mir.ndslice;
2 import numir;
3 import dtree.impurity;
4 import std.stdio;
5 
6 Regression c;
7 auto xs = [-2.0, -1.0, 0.0, 1.0].sliced.unsqueeze!1;
8 auto ys = [-1.0, 0.0, 1.0, 2.0].sliced.unsqueeze!1;
9 c.fit(xs[2], xs, ys, iota(4), 0, 1);
10 
11 assert(c.left.index == [0, 1, 2]);
12 assert(c.right.index == [3]);
13 assert(c.threshold == xs[2][0]);
14 assert(c.left.prediction == [0]);  // mean(-1, 0, 1)
15 assert(c.right.prediction == [2]); // mean(2)
16 assert(c.left.impurity == 2.0);  // ((-1-0)^2+(0-0)^2+(1-0)^2
17 assert(c.right.impurity == 0.0); // (2-2)^2