llamagym 0.1.0

Fine-tuning LLM agents with RL

Fine-tune LLM agents with online reinforcement learning

🐦 Twitter

LlamaGym

LLM agents are called agents—they should be trainable with RL in classic Gym-style environments. But if you try, you'd find it's quite a bit of code to handle LLM conversation context, episode batches, reward assignment, PPO setup, and more.

LlamaGym seeks to simplify fine-tuning LLM agents with RL. Right now, it's a single Agent abstract class that handles all the issues mentioned above, letting you quickly iterate and experiment with agent prompting & hyperparameters across any Gym environment.

Usage

Fine-tuning an LLM-based agent to play in a Gym-style environment with RL has never been easier!

First, implement 3 abstract methods on the Agent class:

class BlackjackAgent(Agent):
    def get_system_prompt(self) -> str:
        return "You are an expert blackjack player."

    def format_observation(self, observation) -> str:
        return f"Your current total is {observation[0]}"

    def extract_action(self, response: str):
        return 0 if "stick" in response else 1

Then, define your base LLM (as you would for any fine-tuning job) and instantiate your agent:

model = AutoModelForCausalLMWithValueHead.from_pretrained("Llama-2-7b").to(device)
tokenizer = AutoTokenizer.from_pretrained("Llama-2-7b")
agent = BlackjackAgent(model, tokenizer, device)

Finally, write your RL loop as usual and simply call your agent to act, reward, and terminate:

env = gym.make("Blackjack-v1")

for episode in trange(5000):
    observation, info = env.reset()
    done = False

    while not done:
        action = agent.act(observation) # act based on observation
        observation, reward, terminated, truncated, info = env.step(action)
        agent.assign_reward(reward) # provide reward to agent
        done = terminated or truncated

    train_stats = agent.terminate_episode() # trains if batch is full

Note: the above code snippets are mildly simplified but a fully working example is available in examples/blackjack.py.

TODO

• set up logging on examples
• understand the PPO logs and fix hyperparams
• run wandb hyperparam sweep