Topic modeling in text is loosely related to the summarization techniques we explored in Chapter 7, Automatic Text Summarization. However, topic modeling involves a more complex mathematical foundation and it produces a different type of result. The goal of text summarization is to produce a version of a text that is reduced but still expresses common themes or concepts in a text, whereas the goal of topic modeling is to expose the underlying concepts themselves.
To extend our Chapter 7, Automatic Text Summarization metaphor, in which text summarization was compared to building a scale model of a house, topic modeling is like trying to describe the purpose of a set of houses based on multiple sample dwellings. For example, the topic model of one neighborhood of houses might be busy family, storage space, and low maintenance and another neighborhood could have houses described with the words social, entertaining, luxury, and showplace. These two models clearly...