ray/rllib/examples/custom_metrics_and_callbacks.py

"""Example of using RLlib's debug callbacks.

Here we use callbacks to track the average CartPole pole angle magnitude as a
custom metric.
"""

import argparse
import numpy as np

import ray
from ray import tune


def on_episode_start(info):
    episode = info["episode"]
    print("episode {} started".format(episode.episode_id))
    episode.user_data["pole_angles"] = []
    episode.hist_data["pole_angles"] = []


def on_episode_step(info):
    episode = info["episode"]
    pole_angle = abs(episode.last_observation_for()[2])
    raw_angle = abs(episode.last_raw_obs_for()[2])
    assert pole_angle == raw_angle
    episode.user_data["pole_angles"].append(pole_angle)


def on_episode_end(info):
    episode = info["episode"]
    pole_angle = np.mean(episode.user_data["pole_angles"])
    print("episode {} ended with length {} and pole angles {}".format(
        episode.episode_id, episode.length, pole_angle))
    episode.custom_metrics["pole_angle"] = pole_angle
    episode.hist_data["pole_angles"] = episode.user_data["pole_angles"]


def on_sample_end(info):
    print("returned sample batch of size {}".format(info["samples"].count))


def on_train_result(info):
    print("trainer.train() result: {} -> {} episodes".format(
        info["trainer"], info["result"]["episodes_this_iter"]))
    # you can mutate the result dict to add new fields to return
    info["result"]["callback_ok"] = True


def on_postprocess_traj(info):
    episode = info["episode"]
    batch = info["post_batch"]
    print("postprocessed {} steps".format(batch.count))
    if "num_batches" not in episode.custom_metrics:
        episode.custom_metrics["num_batches"] = 0
    episode.custom_metrics["num_batches"] += 1


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("--num-iters", type=int, default=2000)
    args = parser.parse_args()

    ray.init()
    trials = tune.run(
        "PG",
        stop={
            "training_iteration": args.num_iters,
        },
        config={
            "env": "CartPole-v0",
            "callbacks": {
                "on_episode_start": on_episode_start,
                "on_episode_step": on_episode_step,
                "on_episode_end": on_episode_end,
                "on_sample_end": on_sample_end,
                "on_train_result": on_train_result,
                "on_postprocess_traj": on_postprocess_traj,
            },
        },
        return_trials=True)

    # verify custom metrics for integration tests
    custom_metrics = trials[0].last_result["custom_metrics"]
    print(custom_metrics)
    assert "pole_angle_mean" in custom_metrics
    assert "pole_angle_min" in custom_metrics
    assert "pole_angle_max" in custom_metrics
    assert "num_batches_mean" in custom_metrics
    assert "callback_ok" in trials[0].last_result