Book Image

Python Machine Learning By Example - Third Edition

By : Yuxi (Hayden) Liu
Book Image

Python Machine Learning By Example - Third Edition

By: Yuxi (Hayden) Liu

Overview of this book

Python Machine Learning By Example, Third Edition serves as a comprehensive gateway into the world of machine learning (ML). With six new chapters, on topics including movie recommendation engine development with Naïve Bayes, recognizing faces with support vector machine, predicting stock prices with artificial neural networks, categorizing images of clothing with convolutional neural networks, predicting with sequences using recurring neural networks, and leveraging reinforcement learning for making decisions, the book has been considerably updated for the latest enterprise requirements. At the same time, this book provides actionable insights on the key fundamentals of ML with Python programming. Hayden applies his expertise to demonstrate implementations of algorithms in Python, both from scratch and with libraries. Each chapter walks through an industry-adopted application. With the help of realistic examples, you will gain an understanding of the mechanics of ML techniques in areas such as exploratory data analysis, feature engineering, classification, regression, clustering, and NLP. By the end of this ML Python book, you will have gained a broad picture of the ML ecosystem and will be well-versed in the best practices of applying ML techniques to solve problems.
Table of Contents (17 chapters)
15
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16
Index

Thinking about features for text data

From the preceding analysis, we can safely conclude that, if we want to figure out whether a document was from the rec.autos newsgroup, the presence or absence of words such as cardoors, and bumper can be very useful features. The presence or not of a word is a Boolean variable, and we can also look at the count of certain words. For instance, car occurs multiple times in the document. Maybe the more times such a word is found in a text, the more likely it is that the document has something to do with cars.

Counting the occurrence of each word token

It seems that we are only interested in the occurrence of certain words, their count, or a related measure, and not in the order of the words. We can therefore view a text as a collection of words. This is called the Bag of Words (BoW) model. This is a very basic model, but it works pretty well in practice. We can optionally...