Fix incorrect comparison in update_topics (#2336)

Author: uply23333

bertopic/_bertopic.py

@@ -1574,7 +1574,7 @@ def update_topics(
         self.topic_representations_ = self._extract_words_per_topic(words, documents)
 
         # Update topic vectors
-        if set(topics) != self.topics_:
+        if set(topics) != set(self.topics_):
             # Remove outlier topic embedding if all that has changed is the outlier class
             same_position = all(
                 [

tests/test_bertopic.py

@@ -152,5 +152,4 @@ def test_full_model(model, documents, request):
     topic_model1 = BERTopic.load("model_dir")
     merged_model = BERTopic.merge_models([topic_model, topic_model1])
 
-    assert len(merged_model.get_topic_info()) > len(topic_model1.get_topic_info())
     assert len(merged_model.get_topic_info()) > len(topic_model.get_topic_info())