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

Introduction to CBOW

The neural network of CBOW is shown in Figure 7.7. It looks like the mirror image of SG. The input layer consists of words that are adjacent to the target words. Again, we are interested in the weights in the hidden layer. They will be the word embeddings.

Figure 7.7 – The structure of a CBOW model

Figure 7.7 – The structure of a CBOW model

The word pairs of the input words and the output words become the pairs as shown in Figure 7.8. They are just the reverse of the word pairs in Figure 7.5. The structure of the neural network is reversed too. Between the hidden layer and the output layer is a 300 x 10,000 weight matrix. This weight matrix is what we are interested in because it has the vector encodings of all the unique words. If we inspect carefully, we will see most of the input nodes are zeros; the weights coming from the non-zero input nodes are the ones contributing to the hidden layer. The ith row in the weight matrix is the weight for the ith word.

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