Gini Splits

Route a New Row

A one-split tree is used by following the displayed branch to a leaf. This lesson shows that path and the exact leaf vote share.

highlighted = computed this step

Start at the root

The new row has Feature A on the left branch. The route is read from the same root split chosen earlier.

Feature A→left\text{Feature A}\rightarrow\text{left}
Route a new rowA new row follows one displayed branch to one leaf.Feature A route for one new rownew row: Feature A=leftFeature A?counts=[3, 3]left | rightleft leafcounts=[2, 1]leaf label=positivevote=2/3right leafcounts=[1, 2]leaf label=negativevote=2/3route: leftone displayed route only

Read the routed leaf

The left leaf contains counts [2,1]. Its majority class is positive with exact vote share 2/3.

left leaf=[2,1],vote=2/3\text{left leaf}=[2,1],\quad \text{vote}=2/3
Route a new rowA new row follows one displayed branch to one leaf.Feature A route for one new rownew row: Feature A=leftFeature A?counts=[3, 3]left | rightleft leafcounts=[2, 1]leaf label=positivevote=2/3right leafcounts=[1, 2]leaf label=negativevote=2/3route: leftone displayed route only

Contrast the other leaf

The right leaf stays visible as a contrast: counts [1,2] give negative majority with vote share 2/3. This is one displayed route only.

right leaf=[1,2],vote=2/3\text{right leaf}=[1,2],\quad \text{vote}=2/3
Route a new rowA new row follows one displayed branch to one leaf.Feature A route for one new rownew row: Feature A=leftFeature A?counts=[3, 3]left | rightleft leafcounts=[2, 1]leaf label=positivevote=2/3right leafcounts=[1, 2]leaf label=negativevote=2/3route: leftone displayed route only