A working knowledge of Python and game development is essential. A good PC with a GPU would be beneficial.

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packtpub.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the Support tab.
3. Click on Code Downloads.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Hands-On-Reinforcement-Learning-for-Games. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: http://www.packtpub.com/sites/default/files/downloads/9781839214936_ColorImages.pdf.

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "The three functions make_atari, wrap_deepmind, and wrap_pytorch are all located in the new wrappers.py file we imported earlier."

A block of code is set as follows:

env_id = 'PongNoFrameskip-v4'
env = make_atari(env_id)
env = wrap_deepmind(env)
env = wrap_pytorch(env)

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

epsilon_start = 1.0
epsilon_final = 0.01
epsilon_decay = 30000

epsilon_by_episode = lambda episode: epsilon_final + (epsilon_start - epsilon_final) * math.exp(-1. * episode / epsilon_decay)

plt.plot([epsilon_by_episode(i) for i in range(1000000)])
plt.show()

Any command-line input or output is written as follows:

pip install mujoco

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Building on that, we'll look at a variant of the DQN called the DDQN, or double (dueling) DQN."