Book Image

Python Natural Language Processing Cookbook

By : Zhenya Antić
Book Image

Python Natural Language Processing Cookbook

By: Zhenya Antić

Overview of this book

Python is the most widely used language for natural language processing (NLP) thanks to its extensive tools and libraries for analyzing text and extracting computer-usable data. This book will take you through a range of techniques for text processing, from basics such as parsing the parts of speech to complex topics such as topic modeling, text classification, and visualization. Starting with an overview of NLP, the book presents recipes for dividing text into sentences, stemming and lemmatization, removing stopwords, and parts of speech tagging to help you to prepare your data. You’ll then learn ways of extracting and representing grammatical information, such as dependency parsing and anaphora resolution, discover different ways of representing the semantics using bag-of-words, TF-IDF, word embeddings, and BERT, and develop skills for text classification using keywords, SVMs, LSTMs, and other techniques. As you advance, you’ll also see how to extract information from text, implement unsupervised and supervised techniques for topic modeling, and perform topic modeling of short texts, such as tweets. Additionally, the book shows you how to develop chatbots using NLTK and Rasa and visualize text data. By the end of this NLP book, you’ll have developed the skills to use a powerful set of tools for text processing.
Table of Contents (10 chapters)

Representing texts with TF-IDF

We can go one step further and use the TF-IDF algorithm to count words and ngrams in incoming documents. TF-IDF stands for term frequency-inverse document frequency and gives more weight to words that are unique to a document than to words that are frequent, but repeated throughout most documents. This allows us to give more weight to words uniquely characteristic to particular documents. You can find out more at https://scikit-learn.org/stable/modules/feature_extraction.html#tfidf-term-weighting.

In this recipe, we will use a different type of vectorizer that can apply the TF-IDF algorithm to the input text. Like the CountVectorizer class, it has an analyzer that we will use to show the representations of new sentences.

Getting ready

We will be using the TfidfVectorizer class from the sklearn package. We will also be using the stopwords list from Chapter 1, Learning NLP Basics.

How to do it…

The TfidfVectorizer class allows for...