Fix Grid Search best model selection

Author: andrewdalpino

CHANGELOG.md

@@ -1,3 +1,6 @@
+- 1.3.5
+    - Fix Grid Search best model selection
+
 - 1.3.4
     - Fix Decision Tree max height terminating condition
 

composer.json

@@ -92,7 +92,10 @@
     "config": {
         "preferred-install": "dist",
         "sort-packages": true,
-        "process-timeout": 3000
+        "process-timeout": 3000,
+        "allow-plugins": {
+            "phpstan/extension-installer": true
+        }
     },
     "funding": [
         {

src/GridSearch.php

@@ -284,7 +284,7 @@ public function train(Dataset $dataset) : void
 
         $scores = $this->backend->process();
 
-        array_multisort($scores, $combinations, SORT_DESC);
+        array_multisort($scores, SORT_DESC, $combinations);
 
         $best = reset($combinations) ?: [];
 

tests/GridSearchTest.php

@@ -140,5 +140,13 @@ public function trainPredictBest() : void
         $score = $this->metric->score($predictions, $testing->labels());
 
         $this->assertGreaterThanOrEqual(self::MIN_SCORE, $score);
+
+        $expectedBest = [
+            'k' => 10,
+            'weighted' => true,
+            'kernel' => new Manhattan(),
+        ];
+
+        $this->assertEquals($expectedBest, $this->estimator->base()->params());
     }
 }