Minor things

1 files changed, 5 insertions, 5 deletions

diff --git a/assignment1.py b/assignment1.py
index 8c5c746..4b264d7 100644
--- a/assignment1.py
+++ b/assignment1.py
@@ -55,6 +55,7 @@ class Node:
         leaf node
         """
         self.col = None
+        # This weird numpy line gives the majority vote, which is 1 or 0
         self.split_value_or_rows = np.argmax(
             np.bincount(node_classes.astype(int)))
 
@@ -198,9 +199,6 @@ def bestsplit(x, y, min_leaf) -> None:
     # twee "x rows" arrays we moeten returnen, en welke split value het beste
     # was natuurlijk.
 
-    # Nodig voor de delta i formule
-    impurity_parent, n_classes_parent = impurity(y), len(y)
-
     # Hieren stoppen we (delta_i, split_value, rows_left, rows_right)
     best_list = []
     # Stop wanneer de array met split points leeg is
@@ -220,10 +218,12 @@ def bestsplit(x, y, min_leaf) -> None:
             split_points = split_points[:-1]
             continue
 
-        # delta_i formule
+        # delta_i formule, improved by not taking the parent impurity into
+        # account, and not making the weighted average but the weigthed sum
+        # only (thanks Lonnie)
         delta_i = (
             impurity(classes_left) * len(classes_left) +
-            impurity(classes_right) * len(classes_right)) / n_classes_parent
+            impurity(classes_right) * len(classes_right))
         # stop huidige splits in de lijst om best split te berekenen
         best_list.append((delta_i, mask_left, mask_right, split_value))
         # Haal de huidige split_point uit split_points