Added hybrid search

simple_search_engine/search_engine.py

@@ -84,6 +84,13 @@ class SimpleSearchEngine:
         self.bm25 = BM25Okapi(self._bm25_tokens)
         print("BM25 index built.")
 
+    def _minmax_normalize(self, scores: np.ndarray):
+    min_s = scores.min()
+    max_s = scores.max()
+    if max_s == min_s:
+        return np.zeros_like(scores)
+    return (scores - min_s) / (max_s - min_s)
+
     def search_bm25(self, query: str, top_k: int = 5):
         if self.bm25 is None:
             raise RuntimeError("BM25 index not built. Call build_index() first.")
@@ -107,6 +114,7 @@ class SimpleSearchEngine:
 
         return results
 
+    # TF-IDF search
     def search(self, query: str, top_k: int = 5):
         if self.vectorizer is None or self.doc_tfidf is None:
             raise RuntimeError("Index not built. Call build_index() first.")
@@ -128,3 +136,38 @@ class SimpleSearchEngine:
             })
 
         return results
+
+    def search_hybrid(self, query: str, top_k: int = 5, alpha: float = 0.5):
+    if self.vectorizer is None or self.doc_tfidf is None or self.bm25 is None:
+        raise RuntimeError("Indexes not built. Call build_index() first.")
+
+    # TF-IDF scores
+    query_vec = self.vectorizer.transform([query])
+    tfidf_scores = linear_kernel(query_vec, self.doc_tfidf).flatten()
+
+    # BM25 scores
+    q_tokens = _tokenize(query)
+    bm25_scores = np.array(self.bm25.get_scores(q_tokens), dtype=float)
+
+    # Normalize
+    tfidf_norm = self._minmax_normalize(tfidf_scores)
+    bm25_norm = self._minmax_normalize(bm25_scores)
+
+    # Combine
+    hybrid_scores = alpha * tfidf_norm + (1 - alpha) * bm25_norm
+
+    ranked_idx = hybrid_scores.argsort()[::-1][:top_k]
+
+    results = []
+    for idx in ranked_idx:
+        doc = self.documents[int(idx)]
+        snippet = doc["text"][:200] + ("..." if len(doc["text"]) > 200 else "")
+        results.append({
+            "score": float(hybrid_scores[int(idx)]),
+            "title": doc["title"],
+            "url": doc["url"],
+            "path": doc["path"],
+            "snippet": snippet,
+        })
+
+    return results