HW2: added run_agent.py, a script that allow load/visualize the train…

…ed agent's performance.

hw2/README.md

@@ -14,3 +14,17 @@ Before doing anything, first replace `gym/envs/box2d/lunar_lander.py` with the p
 The only file that you need to look at is `train_pg_f18.py`, which you will implement.
 
 See the [HW2 PDF](http://rail.eecs.berkeley.edu/deeprlcourse/static/homeworks/hw2.pdf) for further instructions.
+
+
+## Running trained agent
+After running `train_pg_f18.py` with a specific setting (gym environment, metaprameters) a new directory will 
+be added under `data` with the following structure:
+```
+args.exp_name + '_' + args.env_name + '_' + time.strftime("%d-%m-%Y_%H-%M-%S")
+```
+Under this directory, there are multiple (exact number is set by 'n_experiments' param) trained agents. 
+In order to visualize (render) these agents behavior, run the `run_agent.py` script and specify the number of iterations (-n option). For example:
+```bash
+# Run 3 iterations of a agent number 1 of 
+python run_agent.py "data/hc_b4000_r0.01_RoboschoolInvertedPendulum-v1_21-07-2019_08-42-10/1" -n 3
+```

hw2/run_agent.py

@@ -0,0 +1,150 @@
+"""
+## Running trained agent
+After running `train_pg_f18.py` with a specific setting (gym environment, metaprameters) a new directory will
+be added under `data` with the following structure:
+
+    args.exp_name + '_' + args.env_name + '_' + time.strftime("%d-%m-%Y_%H-%M-%S")
+
+Under this directory, there are multiple (exact number is set by 'n_experiments' param) trained agents.
+In order to visualize (render) these agents behavior, run the `run_agent.py` script and specify the number of iterations (-n option). For example:
+
+> python run_agent.py "data/hc_b4000_r0.01_RoboschoolInvertedPendulum-v1_21-07-2019_08-42-10/1" -n 3
+
+"""
+import os
+import json
+import pickle
+import gym
+import numpy as np
+import tensorflow as tf
+from train_pg_f18 import Agent
+
+
+PARAMS_FILE = "params.json"
+VARS_FILE = "vars.pkl"
+
+
+def load_params(filename):
+    """
+    Load the 'params.json' file.
+
+    A simple json.loads() call does not work here because the file was saved with a special separators.
+
+    :param filename: str
+    :return: dict
+    """
+    with open(filename, 'r') as file:
+        data = file.read().replace(',\n', ',').replace('\t:\t', ':').replace('\n', '')
+
+    return json.loads(data)
+
+
+def load_pickle(filename, mode='rb'):
+    with open(filename, mode=mode) as f:
+        return pickle.load(f)
+
+
+def load_agent_and_env(model_dir):
+    """
+    Load an agent with its pre-trained model and the relevant environment
+
+    Most of the code here is taken from train_pg_f18.py::train_PG() function
+
+    :param model_dir: str (full directory path to the 'params.json' and 'vars.pkl' files)
+    :return: tuple (a tuple of length 2, the Agent instance and the gym env object)
+    """
+    # Load the params json
+    params_file = os.path.join(model_dir, PARAMS_FILE)
+    params = load_params(filename=params_file)
+    print(params)
+
+    # Load the model variables
+    vars_filename = os.path.join(model_dir, VARS_FILE)
+    model_vars = load_pickle(filename=vars_filename)
+    # print(model_vars)
+
+    # Make the gym environment
+    env = gym.make(params['env_name'])
+
+    # Set random seeds
+    seed = params['seed']
+    tf.set_random_seed(seed)
+    np.random.seed(seed)
+    #env.seed(seed)
+
+    # Is this env continuous, or self.discrete?
+    discrete = isinstance(env.action_space, gym.spaces.Discrete)
+
+    # Observation and action sizes
+    ob_dim = env.observation_space.shape[0]
+    ac_dim = env.action_space.n if discrete else env.action_space.shape[0]
+
+    # ========================================================================================#
+    # Initialize Agent
+    # ========================================================================================#
+    computation_graph_args = {
+        'n_layers': params['n_layers'],
+        'ob_dim': ob_dim,
+        'ac_dim': ac_dim,
+        'discrete': discrete,
+        'size': params['size'],
+        'learning_rate': params['learning_rate'],
+    }
+
+    sample_trajectory_args = {
+        'animate': params['animate'],
+        'max_path_length': params['max_path_length'],
+        'min_timesteps_per_batch': params['min_timesteps_per_batch'],
+    }
+
+    estimate_return_args = {
+        'gamma': params['gamma'],
+        'reward_to_go': params['reward_to_go'],
+        'nn_baseline': params['nn_baseline'],
+        'normalize_advantages': params['normalize_advantages'],
+    }
+
+    agent = Agent(computation_graph_args, sample_trajectory_args, estimate_return_args)
+
+    # build computation graph
+    agent.build_computation_graph()
+
+    # tensorflow: config, session, variable initialization
+    agent.init_tf_sess()
+
+    # Override the graph variables with the pre-trained values
+    for g_var in tf.global_variables(scope=None):
+        # Get the saved value and assign it to the tensor
+        value = model_vars[g_var.name]
+        set_variable_op = g_var.assign(value)
+        agent.sess.run(set_variable_op)
+
+    # # Validate that the assignment was successful
+    # for g_var in tf.global_variables(scope=None):
+    #     assert np.array_equal(g_var.eval(), model_vars[g_var.name])
+
+    return agent, env
+
+
+if __name__ == "__main__":
+    """
+    Example usage (after running train_pg_18.py and creating agent 'data' dirs):
+    - python run_agent.py "data/hc_b4000_r0.01_RoboschoolInvertedPendulum-v1_21-07-2019_08-42-10/1" -n 3
+    - python run_agent.py "data/ll_b40000_r0.005_LunarLanderContinuous-v2_21-07-2019_09-59-05/1" -n 3
+    - python run_agent.py "data/hc_b50000_r0.005_RoboschoolHalfCheetah-v1_22-07-2019_20-04-48/1" -n 3
+    """
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('model_dir', type=str, help='A relative path to the data dir of a specific experiment. For eample: "data/ll_b40000_r0.005_LunarLanderContinuous-v2_21-07-2019_09-59-05/1"')
+    parser.add_argument('--n_iter', '-n', type=int, default=3)
+    args = parser.parse_args()
+
+    # Load an agent with its pre-trained model and the relevant environment
+    model_dir = args.model_dir
+    agent, env = load_agent_and_env(model_dir)
+
+    # Run an episode with this loaded agent
+    for i in range(args.n_iter):
+        agent.sample_trajectory(env, animate_this_episode=True)
+    print("done")