[Open AI| CartPole v0 - Simulated Annealing v0

README

Based on treeforms solution here: https://gym.openai.com/evaluations/eval_LjL2QnWCRlmh58dLCpMUTg

Changes:
 - Moved agent into it's own class so can be reused on other problems
 - Each time the best score is hit the best values and updated towards the mean of the best values found so far (required because problem is bounded)
 - Alpha decays when best score is matched (required because problem is bounded)
 - Alpha increases if you neither match nor exceeed the best score (helps get around initial 'wrong' choices by random improvement

Improvements from changes:
 - Repeats no longer needed (but included in class anyway in case it was useful for other problems)
 - Time to find first complete solution reduced
 - Variation after finding first complete solution reduced
 - Time spent with incorrect values at the start from randomly moving in the 'wrong' direction reduced

CartPole-v0.py

import logging
import gym
from SimulatedAnnealing import SimulatedAnnealingAgent


def main():
    logger = logging.getLogger()
    logger.setLevel(logging.DEBUG)

    env = gym.make('CartPole-v0')
    agent = SimulatedAnnealingAgent(env.action_space, repeats=1, decay=0.9, spread=0.3)   # Initialise agent

    outdir = '/tmp/' + agent.name + '-results'
    env.monitor.start(outdir, force=True)

    episode_count = 200
    max_steps = 200
    reward = 0
    done = False

    for i in xrange(episode_count):
        ob = env.reset()

        for j in xrange(max_steps):
            action = agent.act(ob, reward, done)
            ob, reward, done, _ = env.step(action)
            if done:
                break

    # Dump result info to disk
    env.monitor.close()

if __name__ == '__main__':
    main()

SimulatedAnnealing.py

import random

random.seed(0)   # So scores are (slightly) more consistent. Randomness in pole counteracts this a bit

class SimulatedAnnealingAgent(object):
    def __init__(self, action_space, repeats=10, alpha=1, decay=0.9, spread=0.5):
        self.name = 'SimAnn'    # Name to be submitted to OpenAI
        self.action_space = action_space  # Just for consistency with other agents, not used in this case

        self.alpha = alpha  # Learning rate
        self.decay = decay  # Decay in impact of alpha
        self.spread = spread  # Spread of randomness when selecting new values to test
        self.repeats = repeats  # Number of times to repeat testing a value

        self.obs_count = 0  # Number of observation returned (can probably get from the environment somehow)
        self.best = []  # Holds best values (set on first run of action)
        self.test = []  # Holds test values

        self.best_score = 0  # Current max score found
        self.best_count = 0  # Times hit max score (used for bounded problems)
        self.ep_score = 0    # Total score for episode
        self.repeat_count = 0  # Times repeated running test

    # Set the new test values at the start of the episode
    def set_test(self):
        # If less than required repeats than just run again
        if self.repeat_count < self.repeats:
            self.repeat_count += 1
            return self.test

        # Else reset repeat count and set new values based on current best, spread and alpha
        self.repeat_count = 0
        return [self.best[i] + (random.random() - self.spread) * self.alpha for i in range(self.obs_count)]

    # Choose action based on observed values
    def choose_action(self, observation):
        if sum(observation[i] * self.test[i] for i in range(self.obs_count)) > 0:
            return 1

        return 0

    # If get the same ep score then update best to average of all values that have reached the best score
    def update_best(self):
        self.best = [(self.best[i] * self.best_count + self.test[i])/(self.best_count + 1) for i in range(self.obs_count)]
        self.best_count += 1

    # What gets called
    def act(self, observation, reward, done):

        # Set initial values if first time agent is seeing observations
        if self.obs_count == 0:
            self.obs_count = len(observation)
            self.best = [0] * self.obs_count
            self.test = self.best

        # Set new test values for new episode
        if self.ep_score == 0:
            self.test = self.set_test()

        # Select action
        action = self.choose_action(observation)

        # Update episode score
        self.ep_score += reward

        if done:
            # If score is the same as best then the amount of variance in future choices goes down
            # Set the new best to be the average of all the best scores so far (using incremental mean)
            if self.ep_score == self.best_score:
                self.alpha *= self.decay
                self.update_best()

            # If new score is greater then set everything to that
            elif self.ep_score > self.best_score:
                self.best_score = self.ep_score
                self.best = self.test
                self.best_count = 0
                self.alpha *= self.decay

            # If new score isn't >= then increase the spread when selecting values
            # This helps get around issues making incorrect starting decisions but can probably be improved
            else:
                self.alpha /= self.decay

            self.ep_score = 0

        return action

Reproduced here:

• https://gym.openai.com/evaluations/eval_aTZEhwaQd2BD7lgDOrACg
• https://gym.openai.com/evaluations/eval_fBhU8KiRSe275CdVkJLbg
• https://gym.openai.com/evaluations/eval_gZLemQm0SAe1EN2hIPXLgQ

(Reasonable amount of variance; about many times did you run it to get your score?)

Marking as reviewed. Thanks for the submission!

The reason I had so many repeats in mine was to get rid of the large amount of variance. So that it would work 100% of the time.

@gdb: 16 was the first uploaded score. I don't know of a way to determine the score when testing locally without manually coding it in, so I just used the average episode score over 200 eps I was training as my guide whos scores ranged from 170-190

@treeform: I think most of the variance from your original solution came from the alpha value when selecting new solutions only reduced when the new result was > the current best. Because the problem is bounded at 200 after the first time you hit any new values keep being set at the same alpha spread. Using the repeats makes it less likely to hit 200 early on so when you do hit it the alpha level has already decayed enough that your unlikely to start testing away from that.

Merging the best results and increasing alpha were to stop it getting stuck early only on in the process at values of around 10, but those steps can probably be improved which would reduce the variance of the solve episodes

Reproduced here as well :
https://gym.openai.com/evaluations/eval_N2crbGpSOFVu3oRBdXvQ

Is there a paper that explains the details of simulated annealing w.r.t. to RL? A quick google search did not yield anything much useful.

Thanks.

Reproduced here as well:
https://gym.openai.com/evaluations/eval_qPRz1hb2SUOJrybCHKO4BA