Conversion of Python code to Matlab.

Could someone please convert the code below from Python to Matlab?

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from .reward_function_base import BaseRewardFunction

class EventDrivenReward(BaseRewardFunction):

"""

EventDrivenReward

Achieve reward when the following event happens:

- Shot down by missile: -200

- Crash accidentally: -200

- Shoot down other aircraft: +200

"""

def __init__(self, config):

super().__init__(config)

def get_reward(self, task, env, agent_id):

"""

Reward is the sum of all the events.

Args:

task: task instance

env: environment instance

Returns:

(float): reward

"""

reward = 0

if env.agents[agent_id].is_shotdown:

reward -= 200

elif env.agents[agent_id].is_crash:

reward -= 200

for missile in env.agents[agent_id].launch_missiles:

if missile.is_success:

reward += 200

return self._process(reward, agent_id)

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Answer 1

[Jayanti]

Hi Joydev,

In MATLAB, importing classes from other files is handled differently than in Python. Each class is typically defined in its own file with the same name as the class. If “BaseRewardFunction” is defined in a separate file named “BaseRewardFunction.m”, MATLAB will automatically recognize it when you create an instance of “EventDrivenReward”, assuming both files are in the same directory or in MATLAB's path.

Now to derive “EventDrivenReward” from parent class “BaseRewardFunction” use the below syntax.

classdef EventDrivenReward < BaseRewardFunction 

You can refer to the following link for subclass syntax.

https://www.mathworks.com/help/matlab/matlab_oop/subclass-syntax.html

According to your code it will have two methods which will be constructor of “EventDrivenReward” class and “get_reward”.

Below code declares a constructor method for the “EventDrivenReward” class. The @ symbol will invoke the constructor of the superclass on the object being created.

function obj = EventDrivenReward(config) 

    obj@BaseRewardFunction(config); 

end 

Now to declare method named “get_reward” that accepts input as “obj”, “task”, “env”, “agent_id” and return output “reward” use below syntax:

function reward = get_reward(obj, task, env, agent_id) 

You can refer the following official MathWorks documentation on class constructor methods and functions for more information:

https://www.mathworks.com/help/matlab/matlab_oop/class-constructor-methods.html

https://www.mathworks.com/help/matlab/ref/function.html

You can refer to below code to implement "for" loop.

for i = 1:length(env.agents(agent_id).launch_missiles) 

        missile = env.agents(agent_id).launch_missiles(i); 

        if missile.is_success 

            reward = reward + 200; 

        end 

end 

“Length” returns the number of elements along the largest dimension of the input. Refer to below official MathWorks documentation on “length” for more details:

https://www.mathworks.com/help/matlab/ref/double.length.html

Hope it help!