Fixing Division by zero error when sqrt((^2) + equals zero

Author: Lars Hartmann

src/Sentiment/Vader.php

@@ -126,7 +126,12 @@ public function isNegated(array $tokens, bool $includeNt = true) : bool
      */
     public function normalize(float $score, int $alpha=15)
     {
-        $normalizedScore = $score/sqrt(($score^2) + $alpha);
+        $normalizedScore = $score;
+
+        if (sqrt(($score^2) + $alpha > 0)) {
+            $normalizedScore = $score/sqrt(($score^2) + $alpha);
+        }
+
         if ($normalizedScore < -1.0) {
             return -1.0;
         } elseif ($normalizedScore > 1.0) {

tests/TextAnalysis/Sentiment/VaderTest.php

@@ -128,5 +128,28 @@ public function testSentimentScoreKindOfCombo()
 
         $this->assertEquals(0.6197, $sentimentScores['compound']);
     }
+
+    public function testNormalizeZeroSum()
+    {
+        if( getenv('SKIP_TEST')) {
+            return;
+        }
+        $tokens = [
+            'If','the','Fake','News','Opposition','Party',
+            'is','pushing','with','all','their','might',
+            'the','fact','that','President','Trump',
+            '“ignored','early','warnings','about',
+            'the','threat','”','then','why','did',
+            'Media','&','Dems','viciously',
+            'criticize','me','when','I',
+            'instituted','a','Travel','Ban',
+            'on','China','They','said',
+            '“early','&','not','necessary.”','Corrupt','Media'
+        ];
+
+        $sentimentScores = vader($tokens);
+        
+        $this->assertEquals(-1, $sentimentScores['compound']);
+    }
 
 }