JavaCPP Presets for ALE

Introduction

This directory contains the JavaCPP Presets module for:

• The Arcade Learning Environment 0.6.0 https://github.com/mgbellemare/Arcade-Learning-Environment

Please refer to the parent README.md file for more detailed information about the JavaCPP Presets.

Documentation

Java API documentation is available here:

• http://bytedeco.org/javacpp-presets/ale/apidocs/

Sample Usage

Here is a simple example of ALE ported to Java from this C++ source file:

• https://github.com/mgbellemare/Arcade-Learning-Environment/blob/master/doc/examples/sharedLibraryInterfaceExample.cpp

We can use Maven 3 to download and install automatically all the class files as well as the native binaries. To run this sample code, after creating the pom.xml and SharedLibraryInterfaceExample.java source files below, simply execute on the command line:

 $ mvn compile exec:java -Dexec.args="rom_file"

The pom.xml build file

<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.bytedeco.ale</groupId>
    <artifactId>sharedlibraryinterfaceexample</artifactId>
    <version>1.5</version>
    <properties>
        <exec.mainClass>SharedLibraryInterfaceExample</exec.mainClass>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.bytedeco</groupId>
            <artifactId>ale-platform</artifactId>
            <version>0.6.0-1.5</version>
        </dependency>
    </dependencies>
    <build>
        <sourceDirectory>.</sourceDirectory>
    </build>
</project>

The SharedLibraryInterfaceExample.java source file

/* *****************************************************************************
 * A.L.E (Arcade Learning Environment)
 * Copyright (c) 2009-2013 by Yavar Naddaf, Joel Veness, Marc G. Bellemare,
 *  Matthew Hausknecht, and the Reinforcement Learning and Artificial Intelligence 
 *  Laboratory
 * Released under the GNU General Public License; see License.txt for details. 
 *
 * Based on: Stella  --  "An Atari 2600 VCS Emulator"
 * Copyright (c) 1995-2007 by Bradford W. Mott and the Stella team
 *
 * *****************************************************************************
 *  sharedLibraryInterfaceExample.cpp 
 *
 *  Sample code for running an agent with the shared library interface. 
 **************************************************************************** */

import java.lang.System;
import java.util.Random;
import org.bytedeco.javacpp.*;
import org.bytedeco.ale.*;
import static org.bytedeco.ale.global.ale.*;

public class SharedLibraryInterfaceExample {
    public static void main(String[] args) {
        if (args.length < 1) {
            System.err.println("Usage: java SharedLibraryInterfaceExample rom_file");
            System.exit(1);
        }

        ALEInterface ale = new ALEInterface();

        // Get & Set the desired settings
        ale.setInt("random_seed", 123);
        //The default is already 0.25, this is just an example
        ale.setFloat("repeat_action_probability", 0.25f);

        ale.setBool("display_screen", true);
        ale.setBool("sound", true);

        // Load the ROM file. (Also resets the system for new settings to
        // take effect.)
        ale.loadROM(args[0]);

        // Get the vector of legal actions
        IntPointer legal_actions = ale.getLegalActionSet();

        // Play 10 episodes
        Random random = new Random();
        for (int episode = 0; episode < 10; episode++) {
            float totalReward = 0;
            while (!ale.game_over()) {
                int a = legal_actions.get(random.nextInt((int)legal_actions.limit()));
                // Apply the action and get the resulting reward
                float reward = ale.act(a);
                totalReward += reward;
            }
            System.out.println("Episode " + episode + " ended with score: " + totalReward);
            ale.reset_game();
        }

        System.exit(0);
    }
}