Gini Splits

The Tree, One Split Deep

The chosen split becomes a small tree: one root question and two leaves. The diagram keeps the count and impurity audit visible at each node.

highlighted = computed this step

The chosen root question

The tree uses Feature A at the root. The parent counts [3,3] split into two leaves.

root:A\text{root}:A
One split deepThe chosen binary tree shows root and two leaves.Chosen Feature A splitroot splitcounts=[3, 3]G=1/2left leafcounts=[2, 1]G=4/9right leafcounts=[1, 2]G=4/9

Why the leaf labels stay counts

Each leaf displays its own counts and Gini value. The display stays exact because every value is recomputed from integer counts.

leaf G=4/9\text{leaf }G=4/9
One split deepThe chosen binary tree shows root and two leaves.Chosen Feature A splitroot splitcounts=[3, 3]G=1/2left leafcounts=[2, 1]G=4/9right leafcounts=[1, 2]G=4/9

Summary

This is one exact binary split. The diagram shows root counts, child counts, and child impurity without decimals.

Gleaf=4/9G_{\text{leaf}}=4/9
One split deepThe chosen binary tree shows root and two leaves.Chosen Feature A splitroot splitcounts=[3, 3]G=1/2left leafcounts=[2, 1]G=4/9right leafcounts=[1, 2]G=4/9