Topic Modeling: How do I use my fitted LDA model to predict new topics for a new dataset in R?

Question

I am using \'lda\' package in R for topic modeling. I want to predict new topics(collection of related words in a document) using a fitted Latent Dirichlet Allocation(LDA) m

Answer 1

I don't know how you can achieve this in R but please have a look at a 2009 publication by Wallach et. al. titled 'Evaluation Methods for Topic Models' here. Have a look at section 4, it mentions three methods to calculate P(z|w), one based on importance sampling and other two called 'Chib-style estimator' and 'left-to-right estimator'.

Mallet has implementation of left-to-right estimator method