Add word similarity calculation to enhance overall similarity scoring in calculate_similarity function. Implement character matching logic and boost score for same-length words.

similarity_search.c

@@ -55,6 +55,41 @@ void free_words(char *words[], int word_count) {
     }
 }
 
+// Calculate similarity between two words based on character matching
+float word_similarity(const char *word1, const char *word2) {
+    int len1 = strlen(word1);
+    int len2 = strlen(word2);
+    int max_len = len1 > len2 ? len1 : len2;
+    if (max_len == 0) return 0.0f;
+    
+    int matches = 0;
+    int i = 0, j = 0;
+    
+    // Count matching characters (case insensitive)
+    while (i < len1 && j < len2) {
+        if (tolower((unsigned char)word1[i]) == tolower((unsigned char)word2[j])) {
+            matches++;
+            i++;
+            j++;
+        } else if (tolower((unsigned char)word1[i]) < tolower((unsigned char)word2[j])) {
+            i++;
+        } else {
+            j++;
+        }
+    }
+    
+    // Calculate similarity based on matching characters
+    float char_similarity = (float)matches / max_len;
+    
+    // If words are the same length, boost similarity
+    if (len1 == len2) {
+        char_similarity = char_similarity * 1.2f; // 20% boost for same length
+        if (char_similarity > 1.0f) char_similarity = 1.0f;
+    }
+    
+    return char_similarity;
+}
+
 // Calculate similarity between query and target string
 float calculate_similarity(const char *query, const char *target, float cutoff) {
     // Split strings into words
@@ -70,32 +105,43 @@ float calculate_similarity(const char *query, const char *target, float cutoff)
         return 0.0;
     }
     
-    // Count matches and track which query words were found
-    int matches = 0;
+    // Track best matches for each query word
+    float best_word_similarities[MAX_WORDS] = {0.0f};
     int query_words_found = 0;
-    int found_query_words[MAX_WORDS] = {0}; // Track which query words were found
     
+    // For each query word, find its best match in target words
     for (int i = 0; i < query_word_count; i++) {
+        float best_similarity = 0.0f;
+        
         for (int j = 0; j < target_word_count; j++) {
-            if (str_case_cmp(query_words[i], target_words[j]) == 0) {
-                matches++;
-                if (!found_query_words[i]) {
-                    found_query_words[i] = 1;
-                    query_words_found++;
-                }
-                break;
+            float similarity = word_similarity(query_words[i], target_words[j]);
+            if (similarity > best_similarity) {
+                best_similarity = similarity;
             }
         }
+        
+        best_word_similarities[i] = best_similarity;
+        if (best_similarity >= 0.8f) { // Consider it a match if similarity is high enough
+            query_words_found++;
+        }
     }
     
-    // Calculate base similarity (intersection over union)
-    float base_similarity = (float)matches / (query_word_count + target_word_count - matches);
+    // Calculate overall similarity
+    float word_match_score = (float)query_words_found / query_word_count;
     
-    // If all query words were found, boost the similarity
-    float similarity = base_similarity;
-    if (query_words_found == query_word_count) {
-        // If all query words were found, similarity should be at least 0.8
-        similarity = base_similarity > 0.8f ? base_similarity : 0.8f;
+    // Calculate average of best word similarities
+    float avg_word_similarity = 0.0f;
+    for (int i = 0; i < query_word_count; i++) {
+        avg_word_similarity += best_word_similarities[i];
+    }
+    avg_word_similarity /= query_word_count;
+    
+    // Combine scores: 60% weight on word matches, 40% on character similarity
+    float similarity = (word_match_score * 0.6f) + (avg_word_similarity * 0.4f);
+    
+    // If all query words were found with high similarity, ensure high overall score
+    if (query_words_found == query_word_count && avg_word_similarity >= 0.8f) {
+        similarity = 1.0f; // Perfect match
     }
     
     free_words(query_words, query_word_count);