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Python Machine Learning by Example

You're reading from   Python Machine Learning by Example Build intelligent systems using Python, TensorFlow 2, PyTorch, and scikit-learn

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Product type Paperback
Published in Oct 2020
Publisher Packt
ISBN-13 9781800209718
Length 526 pages
Edition 3rd Edition
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Author (1):
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Yuxi (Hayden) Liu Yuxi (Hayden) Liu
Author Profile Icon Yuxi (Hayden) Liu
Yuxi (Hayden) Liu
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Toc

Table of Contents (17) Chapters Close

Preface 1. Getting Started with Machine Learning and Python 2. Building a Movie Recommendation Engine with Naïve Bayes FREE CHAPTER 3. Recognizing Faces with Support Vector Machine 4. Predicting Online Ad Click-Through with Tree-Based Algorithms 5. Predicting Online Ad Click-Through with Logistic Regression 6. Scaling Up Prediction to Terabyte Click Logs 7. Predicting Stock Prices with Regression Algorithms 8. Predicting Stock Prices with Artificial Neural Networks 9. Mining the 20 Newsgroups Dataset with Text Analysis Techniques 10. Discovering Underlying Topics in the Newsgroups Dataset with Clustering and Topic Modeling 11. Machine Learning Best Practices 12. Categorizing Images of Clothing with Convolutional Neural Networks 13. Making Predictions with Sequences Using Recurrent Neural Networks 14. Making Decisions in Complex Environments with Reinforcement Learning 15. Other Books You May Enjoy
16. Index

Solving the Taxi problem with the Q-learning algorithm

Q-learning is also a model-free learning algorithm. It updates the Q-function for every step in an episode. We will demonstrate how Q-learning is used to solve the Taxi environment. It is a typical environment with relatively long episodes. So let's first simulate the Taxi environment.

Simulating the Taxi environment

In the Taxi environment (https://gym.openai.com/envs/Taxi-v3/) the agent acts as a taxi driver to pick up the passenger from one location and drop off the passenger at the destination.

All subjects are on a 5 * 5 grid. Take a look at the following example:

Figure 14.6: Example of the Taxi environment

Tiles in certain colors have the following meanings:

  • Yellow: The location of the empty taxi (without the passenger)
  • Blue: The passenger's location
  • Purple: The passenger's destination
  • Green: The location of the taxi with the passenger

The starting...

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