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

What is cosine similarity?

The similarity of two vectors can be measured using cosine similarity. So, let’s start with vector properties. Given two vectors, one vector can be projected onto another to show “how much” a vector is pointing in the same direction as the other. Figure 5.1 shows a 2D graph of the projection of vector a onto vector b.

Figure 5.1 – The projection of vector a on vector b

Figure 5.1 – The projection of vector a on vector b

It is the shadow of vector a being cast on vector b. If the angle is small, the shadow will be long. It means the two vectors are very close. If the angle is as large as 90 degrees, the shadow is almost 0. It means the two vectors are not related at all. Therefore, the angle between the two vectors can measure the similarity. The length of the shadow is the length of a times the cosine of the angle between the two vectors. We will use the dot product of two vectors to mathematically define the similarity.

The dot product of vectors...