Problem with shape of Child model theta matrix

[NikolayPavlychev]

Problem with shape of Child model theta matrix

[bt2901]

This is expected behaviour for hierarchical models. In that case, ARTM adds 'pseudodocuments' to the collection and tries to factorize this new collection. Each pseudodocument is related to some topic of the parent model (since the distributions p(subtopic|doc) and p(subtopic|parent_topic) are similar computationally). If you run child_model.get_parent_psi(), the Psi matrix you obtain should consist of the "extra" columns of Theta, precisely.

Also, for convergence/memory efficiency reasons the following patter is suggested:

model = artm.ARTM(
            ...
            # cache_theta=False,
            theta_columns_naming='title'
)
model.fit_offline(batch_vectorizer, ...)
theta = model.transform(batch_vectorizer)

The result is pandas DataFrame where the index is topic names, and columns are document names (without pseudodocuments).

You are absolutely correct that this could be made more clear in the documentation.