This project works with the Tennis environment.

In this environment, two agents control rackets to bounce a ball over a net. If an agent hits the ball over the net, it receives a reward of +0.1. If an agent lets a ball hit the ground or hits the ball out of bounds, it receives a reward of -0.01. Thus, the goal of each agent is to keep the ball in play.

The observation space consists of 8 variables corresponding to the position and velocity of the ball and racket. Each agent receives its own, local observation. Two continuous actions are available, corresponding to movement toward (or away from) the net, and jumping.

The task is episodic, and in order to solve the environment, the two agents must get an average score of +0.5 (over 100 consecutive episodes, after taking the maximum over both agents). Specifically,

• After each episode, we add up the rewards that each agent received (without discounting), to get a score for each agent. This yields 2 (potentially different) scores. We then take the maximum of these 2 scores.
• This yields a single score for each episode.

The environment is considered solved, when the average (over 100 episodes) of those scores is at least +0.5.

INFO:unityagents:
'Academy' started successfully!
Unity Academy name: Academy
        Number of Brains: 1
        Number of External Brains : 1
        Lesson number : 0
        Reset Parameters :
		
Unity brain name: TennisBrain
        Number of Visual Observations (per agent): 0
        Vector Observation space type: continuous
        Vector Observation space size (per agent): 8
        Number of stacked Vector Observation: 3
        Vector Action space type: continuous
        Vector Action space size (per agent): 2
        Vector Action descriptions: , 

Python 3.6 is required. The program requires PyTorch, the ML-Agents toolkit, and a few more Python packages required to complete the project.

git clone https://github.com/udacity/deep-reinforcement-learning.git  
cd deep-reinforcement-learning/python  
pip install .

Run the following to create drlnd kernel in ipython so that the right unity environment is loaded correctly

python -m ipykernel install --user --name drlnd --display-name "drlnd"

Pytorch can be installed with the commands recommended in https://pytorch.org/ for the respective OS. Fo example for Conda package installling into a Windows environment with Python 3.6 is: ''' conda install pytorch -c pytorch '''

Place Report.ipynb in the folder p3_collab-compet/ together with the following two files:

1. ddpg_agent.py - contains the DDPG agent code.
2. model.py - contains Actor and Critic neural network modules classes

The Unity Reacher environment can be downloaded from here:

• Linux: click here
• Mac OSX: click here
• Windows (32-bit): click here
• Windows (64-bit): click here

(For Windows users) Check out this link if you need help with determining if your computer is running a 32-bit version or 64-bit version of the Windows operating system.

Choose the environment suitable for your machine. Unzipping will create another Tennis_XXX folder. For example, if the Tennis Windows 64-bits environment is downloaded, Tennis_Windows_x86_64 will be created.

Run p3_collab-compet/Report.ipynb

Enter the right path for the Unity Tennis environment in Report.ipynb. For example for a folder consisting a Windows 64-bits environemnt is:

env = UnityEnvironment(file_name="./Tennis_Windows_x86_64/Tennis.exe")

Run the remaining cell as ordered in Report.ipynb to train the Actor-Critic DDPG agent.