Book Image

The Handbook of NLP with Gensim

By : Chris Kuo
Book Image

The Handbook of NLP with Gensim

By: Chris Kuo

Overview of this book

Navigating the terrain of NLP research and applying it practically can be a formidable task made easy with The Handbook of NLP with Gensim. This book demystifies NLP and equips you with hands-on strategies spanning healthcare, e-commerce, finance, and more to enable you to leverage Gensim in real-world scenarios. You’ll begin by exploring motives and techniques for extracting text information like bag-of-words, TF-IDF, and word embeddings. This book will then guide you on topic modeling using methods such as Latent Semantic Analysis (LSA) for dimensionality reduction and discovering latent semantic relationships in text data, Latent Dirichlet Allocation (LDA) for probabilistic topic modeling, and Ensemble LDA to enhance topic modeling stability and accuracy. Next, you’ll learn text summarization techniques with Word2Vec and Doc2Vec to build the modeling pipeline and optimize models using hyperparameters. As you get acquainted with practical applications in various industries, this book will inspire you to design innovative projects. Alongside topic modeling, you’ll also explore named entity handling and NER tools, modeling procedures, and tools for effective topic modeling applications. By the end of this book, you’ll have mastered the techniques essential to create applications with Gensim and integrate NLP into your business processes.
Table of Contents (24 chapters)
1
Part 1: NLP Basics
5
Part 2: Latent Semantic Analysis/Latent Semantic Indexing
9
Part 3: Word2Vec and Doc2Vec
12
Part 4: Topic Modeling with Latent Dirichlet Allocation
18
Part 5: Comparison and Applications

Using the coherence score to find the optimal number of topics

The previous section arbitrarily set the number of topics as 20. Is this the optimal number of topics? To investigate this, we need to understand the “scope” of a topic. A topic can have a set of words that are loosely connected, or closely connected. The latter is a distinctive topic, but the former is not distinctive enough. In other words, the “closeness” of words in a topic is an important measure. If a topic has words that are very loosely connected, the topic may be better separated into more than one.

In order to measure the “closeness” of a topic, Röder, Both, and Hinneburg (2015) [5] proposed a metric called the coherence score. The score is defined as the average or median of pairwise word similarities, formed by the top words of a given topic. The value of a coherence score itself doesn’t have a universal meaning because it varies, based on the scoring...