Sentiment computation now returns undefined if there is no sentiment data

Author: mlomb

pipeline/process/nlp/Emojis.ts

@@ -18,9 +18,9 @@ export class Emojis {
         return this.data[emoji] ? this.data[emoji].n : emoji;
     }
 
-    /** Returns the sentiment of an emoji. e.g. 😡 → negative, ❤ → positive, 🟪 → 0. Always [-1, 1] */
-    public getSentiment(emoji: string): number {
-        return this.data[emoji]?.s || 0;
+    /** Returns the sentiment of an emoji. e.g. 😡 → negative, ❤ → positive, 🟪 → undefined. Always [-1, 1] */
+    public getSentiment(emoji: string): number | undefined {
+        return this.data[emoji]?.s;
     }
 
     static async load(env: Env) {

pipeline/process/nlp/Sentiment.ts

@@ -66,6 +66,7 @@ export class Sentiment {
         let score = 0;
         let nearNegator = false;
         let nearNegatorDist = 0;
+        let tokenHits = 0;
 
         for (let i = 0, len = tokens.length; i < len; i++) {
             const token = tokens[i];
@@ -76,7 +77,11 @@ export class Sentiment {
             nearNegatorDist++;
 
             if (token.tag === "emoji") {
-                score += this.emojiData.getSentiment(token.text);
+                const emojiValue = this.emojiData.getSentiment(token.text);
+                if (emojiValue !== undefined) {
+                    tokenHits++;
+                    score += emojiValue;
+                }
                 continue;
             }
 
@@ -93,12 +98,14 @@ export class Sentiment {
 
                 const afinnMatch = langDb.afinn.match(slice);
                 if (afinnMatch) {
+                    tokenHits++;
                     score += afinnMatch.value * (nearNegator ? -1 : 1);
                 }
             }
         }
 
-        return score;
+        // only return score if we found at least one token with sentiment
+        return tokenHits > 0 ? score : undefined;
     }
 
     static async load(env: Env, emojis: Emojis) {

tests/process/nlp/Emojis.test.ts

@@ -17,6 +17,6 @@ describe("Emojis", () => {
     it("should return correct sentiment for common emojis", async () => {
         expect(emojis.getSentiment("😡")).toBeNegative();
         expect(emojis.getSentiment("❤")).toBePositive();
-        expect(emojis.getSentiment("🟪")).toBe(0); // rare emoji
+        expect(emojis.getSentiment("🟪")).toBe(undefined); // rare emoji
     });
 });