c_tf_idf_ is None when using zero shot topic modeling.

[ishansuryan]

I am using zero shot topic modeling using bertopic and i also want hierarchical topic representation but When i run the model.hierarchical_topics(array of strings) the following errors is what i get:

TypeError: 'NoneType' object is not subscriptable

TypeError Traceback (most recent call last)
File , line 1
----> 1 model.hierarchical_topics(array of strings)

File /local_disk0/.ephemeral_nfs/cluster_libraries/python/lib/python3.10/site-packages/bertopic/bertopic.py:975, in BERTopic.hierarchical_topics(self, docs, linkage_function, distance_function)
972 linkage_function = lambda x: sch.linkage(x, 'ward', optimal_ordering=True)
974 # Calculate distance
--> 975 embeddings = self.c_tf_idf[self._outliers:]
976 X = distance_function(embeddings)
977 X = validate_distance_matrix(X, embeddings.shape[0])

TypeError: 'NoneType' object is not subscriptable

[MaartenGr]

This is in essence the same issue as #1999 where you can find a temporary fix. A more permanent fix will follow but that needs to be discussed still.