decisionrl 0.2.0

Applied reinforcement learning for operational decisions: pricing, inventory, energy, queues and supply chains — plus a correctness-first library of 31 algorithms.

decisionrl

Reinforcement learning for operational decisions.

Most RL libraries are built for games and robots — Atari, MuJoCo, control suites. decisionrl is built for the decisions businesses actually make: pricing, inventory, energy, queueing and supply chains. It ships the environments, the baselines to beat, and the proof — on top of a dependency-light, correctness-first library of 31 algorithms.

Applied environments with baselines · a correctness-first library of 31 algorithms · one clean, tested, typed package.

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Why decisionrl

Pick up SB3 or CleanRL and you get Atari and MuJoCo. Real operational problems — "what price today?", "how much to reorder?", "charge or discharge the battery?", "admit this job or shed it?" — you build yourself. decisionrl ships them as first-class environments, each with the classic baseline (base-stock, bang-bang, best fixed price, admit-all) so you can prove the learned policy is better, not just assert it:

Applied task	Learned (RL)	Classic baseline
📦 Inventory management	194.5 profit	196.7 · best base-stock
🏷️ Dynamic pricing	24.6 revenue	11.5 · random pricing
🎛️ Queue admission control	25.6 value	−16.2 · admit-all
🌡️ Thermostat / HVAC	−35.8 return	−304.0 · bang-bang
🔋 Energy microgrid (battery)	21.3 return	13.1 · no battery
🚚 Supply chain (2-echelon)	−31.3 return	−175.5 · order-nothing

RL beats the naive baseline on five of six and recovers the operations-research optimum on inventory (it matches the analytic base-stock policy from scratch, with no domain knowledge).

Every number above is reproduced by examples/applied_rl_demo.py on CPU in a few minutes. Under the hood it's a full RL library — 31 algorithms, from tabular Q-learning to PPO/SAC/TRPO, offline RL, model-based, multi-agent and meta-RL — so once a problem outgrows the built-ins you don't switch tools.

Overview

flowchart LR
    subgraph Interaction
        Env["Environment<br/>Applied: Pricing · Inventory · Energy · Queue · SupplyChain<br/>Control: CartPole · Pendulum · GridWorld · Gymnasium"]
        Agent["Agent<br/>predict / learn / save / load"]
        Env -- "obs, reward, done" --> Agent
        Agent -- "action" --> Env
    end
    Agent --> Buf["Buffers<br/>Replay · PER · n-step · Rollout (GAE)"]
    Net["Networks<br/>MLP · CNN · Dueling · Categorical<br/>Gaussian · Noisy · Ensemble"] --> Agent
    Buf --> Learn["Learner update<br/>TD · PPO/GAE · V-trace · SAC · CQL · imagination"]
    Learn -- "gradients" --> Net
    Agent --> Log["Logger → CSV · TensorBoard · W&B · Plotly dashboard"]

    Vec["Vector envs (sync / async / distributed actors)"] -.-> Env
    Tune["Optuna search · CLI · tuned configs"] -.-> Agent

Algorithm zoo

mindmap
  root(("decisionrl"))
    Tabular
      Q-Learning
      SARSA
      Expected SARSA
    Model-based
      Dyna-Q
      MBPO
      Dreamer exp
    Value-based
      DQN
      C51
      QR-DQN
      Rainbow
    Policy actor-critic
      REINFORCE
      A2C
      PPO
      TRPO
      GRPO
      IMPALA
      Recurrent PPO
      SAC-Discrete
    Continuous
      DDPG
      TD3
      SAC
    Offline
      TD3-BC
      IQL
      CQL
      Decision Transformer
    Multi-agent
      MAPPO
      self-play IPPO

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Core RL sanity checks

The applied results above are the point; these are the classic-control sanity checks every RL library is expected to pass — reassurance that the algorithms are correct. Each figure is produced by a single command — python examples/benchmark.py — which trains four agents on four control tasks from scratch on CPU in a few minutes and renders the plots.

Task	Algorithm	Result
CartPole (balance)	PPO	solved — return 500 / 500
GridWorld 5×5 (navigate)	DQN (Double + Dueling)	near-optimal — return ≈ 0.93
Pendulum (swing-up)	SAC	improves from ≈ −1300 to ≈ −420
GridWorld 4×4 (navigate)	Q-Learning	optimal — return ≈ 0.95

The tabular agent recovers the optimal navigation policy (every arrow flows to the goal):

Watch trained agents

PPO balances CartPole · SAC swings up Pendulum · Q-Learning navigates GridWorld — all rendered by python examples/record_gifs.py.

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Applied solutions

The flagship of decisionrl: six environments that model real operational decisions, each shipped with the classic operations-research baseline so a learned policy can be proved better. Train all six and print the proof table with python examples/applied_rl_demo.py; the two flagship figures below come from python examples/applied_demo.py.

Applied task	What the agent decides	Baseline to beat
📦 Inventory management	how much to reorder	base-stock ("order up to S")
🏷️ Dynamic pricing	what price to set	best fixed price
🎛️ Queue admission control	admit or shed each job	admit-all
🌡️ Thermostat / HVAC	heating/cooling power	bang-bang
🔋 Energy microgrid	charge/discharge a battery	no battery
🚚 Supply chain (2-echelon)	orders across the chain	per-echelon base-stock

📦 Inventory management (operations research)

An agent sets weekly re-order quantities under stochastic (Poisson) demand, trading off holding cost, ordering cost and stockouts. PPO recovers the optimal base-stock policy from scratch — it matches the analytic heuristic (≈ 195 vs 197 profit) and crushes a random policy (≈ 160), with zero domain knowledge.

🌡️ Thermostat / HVAC control (energy)

An agent modulates a heating/cooling unit to hold a room at its setpoint while the outdoor temperature swings on a daily cycle. SAC tracks the setpoint smoothly using about ⅓ of the energy of a bang-bang thermostat (return ≈ −36 vs −304; energy ≈ 59 vs 200).

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Complex scenarios

Beyond the toy tasks, decisionrl ships four harder, higher-dimensional environments from distinct domains — richer observations, non-linear dynamics and real exploration / credit-assignment challenges. Train them all with python examples/complex_scenarios.py (uses the GPU automatically). Measured results (random start → after training):

Scenario	Domain	Obs · Action	Algorithm	Return: before → after
🦾 ReacherArm	robotic manipulation	Box(10) · Box(2)	SAC	−8.1 → −5.6
🧭 Navigation2D (lidar maze)	navigation / hard exploration	Box(14) · Box(2)	SAC	−9.5 → +5.0 (reaches goal)
🚀 LunarLander	rocket soft-landing	Box(8) · Discrete(4)	PPO	−435 → +79 (lands)
📈 PortfolioAllocation	finance / allocation	Box(4n) · Box(n)	SAC	beats equal-weight (≈ +1.5 vs ≈ 0, momentum market)

Each is self-contained (NumPy only, Gymnasium API) — see the environments docs. Navigation2D pairs naturally with the curiosity bonuses for sparse-reward exploration.

Trained agents in action (record with examples/record_scenario_gifs.py):

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Design principles

The applied focus sits on a deliberately engineered core: every algorithm is short and legible, but built from shared, swappable components (buffers, networks, policies, schedules, wrappers). Three principles guide it:

1. Correctness-first. The subtle things that quietly break RL agents are handled properly — most notably the Gymnasium terminated vs truncated distinction, which is bootstrapped correctly everywhere (time-limit truncation bootstraps from the final observation; true termination does not). It also ships GAE, target-policy smoothing, automatic entropy tuning, orthogonal init, advantage normalization and observation/reward normalization.
2. Dependency-light & batteries-included. The core needs only NumPy + PyTorch. Built-in environments (GridWorld, bandit, CartPole, Pendulum, PointMass) mean you can train an agent end-to-end with zero extra installs. Gymnasium is an optional extra, not a requirement.
3. One API for everything. Tabular or deep, discrete or continuous, on-policy or off-policy — every agent exposes the same four methods: predict · learn · save · load.

Installation

# from PyPI — distributed as "decisionrl", imported as "decisionrl"
pip install decisionrl

# with Gymnasium environments
pip install "decisionrl[gym]"

# latest from source
pip install git+https://github.com/DenisDrobyshev/decisionrl.git

# local dev install
git clone https://github.com/DenisDrobyshev/decisionrl.git
cd decisionrl
pip install -e ".[dev]"

One name everywhere: the PyPI distribution, the import package and the repo are all decisionrl.

Quick start

Applied RL — learn an operational policy and beat the textbook heuristic:

from decisionrl import make_env, make_agent
from decisionrl.training import evaluate_policy

# how much to reorder each week under stochastic demand
env = make_env("InventoryManagement")
agent = make_agent("ppo", env, seed=0).learn(40_000)
print(evaluate_policy(agent, make_env("InventoryManagement"), n_episodes=20))
# -> profit on par with the optimal base-stock policy, learned from scratch

The same four-method API (predict / learn / save / load) covers classic control too:

from decisionrl.algorithms import PPO
from decisionrl.envs import CartPole
from decisionrl.training import evaluate_policy
from decisionrl.utils import set_seed

set_seed(0)
agent = PPO(CartPole(), n_steps=1024, seed=0)
agent.learn(total_steps=50_000)

mean, std = evaluate_policy(agent, CartPole(), n_episodes=20)
print(f"return = {mean:.1f} +/- {std:.1f}")

agent.save("ppo_cartpole.pt")
agent = PPO.load("ppo_cartpole.pt", env=CartPole())

Tabular control is just as simple:

from decisionrl.algorithms import QLearning
from decisionrl.envs import GridWorld

agent = QLearning(GridWorld(rows=5, cols=5), seed=0)
agent.learn(total_steps=20_000)

Continuous control with SAC:

from decisionrl.algorithms import SAC
from decisionrl.envs import Pendulum

agent = SAC(Pendulum(), seed=0)
agent.learn(total_steps=20_000)

Use a Gymnasium environment (optional extra):

from decisionrl.algorithms import PPO
from decisionrl.envs import make_gym

agent = PPO(make_gym("CartPole-v1"), seed=0)
agent.learn(total_steps=100_000)

Scale on-policy training with vectorized environments:

from decisionrl.algorithms import PPO
from decisionrl.envs import CartPole
from decisionrl.wrappers import SyncVectorEnv

venv = SyncVectorEnv([lambda: CartPole() for _ in range(8)])
agent = PPO(venv, n_steps=256, seed=0)   # 8 x 256 = 2048 steps per update
agent.learn(total_steps=200_000)

Command-line interface

Train and evaluate without writing a script — tuned default hyperparameters are applied automatically per (algorithm, environment) and can be overridden:

decisionrl list                                          # show algorithms & envs
decisionrl train ppo CartPole --steps 50000 --save ppo.pt --progress
decisionrl train dqn CartPole --set learning_rate=5e-4 --set buffer_size=100000
decisionrl train ppo CartPole --n-envs 8 --async         # parallel data collection
decisionrl eval ppo --env CartPole --load ppo.pt --episodes 20
decisionrl play ppo --env CartPole --load ppo.pt        # watch the trained agent
decisionrl train ppo gym:LunarLander-v2 --steps 200000   # any Gymnasium env
decisionrl dashboard run.csv                             # live web dashboard (reward/loss)

decisionrl dashboard <metrics.csv> serves a lightweight live dashboard (Flask + Plotly) that auto-refreshes one chart per metric as training writes the CSV.

Programmatic equivalents via the registry:

from decisionrl import make_env, make_agent, make_vec_env
agent = make_agent("ppo", make_env("CartPole"), seed=0).learn(50_000)
venv = make_vec_env("CartPole", n_envs=8, asynchronous=True)   # one-line vectorization

Training utilities & callbacks

from decisionrl.algorithms import PPO
from decisionrl.envs import CartPole
from decisionrl.training import ProgressBarCallback, EvalCallback, CheckpointCallback, CallbackList

agent = PPO(CartPole(), anneal_lr=True, seed=0)      # linear LR decay (best practice)
agent.learn(100_000, callback=CallbackList([
    ProgressBarCallback(),                            # live tqdm bar (steps/s, ETA, return)
    EvalCallback(CartPole(), eval_freq=5000, best_model_save_path="best.pt"),
    CheckpointCallback(save_freq=20_000, save_dir="checkpoints"),
]))

Algorithms

Family	Algorithm	Class	Action space	Key features
Tabular	Q-Learning	QLearning	Discrete	off-policy TD
Tabular	SARSA	SARSA	Discrete	on-policy TD
Tabular	Expected SARSA	ExpectedSARSA	Discrete	lower-variance TD
Model-based	Dyna-Q	DynaQ	Discrete	learned model + planning (Sutton 1990)
Model-based	MBPO	MBPO	Continuous	ensemble dynamics + short rollouts + SAC
Model-based	Dreamer*	Dreamer	Continuous	latent world model + imagination (*experimental)
Model-based	DreamerRSSM*	DreamerRSSM	Continuous	RSSM world model (GRU + stochastic latent + KL) (*experimental)
Value-based	DQN	DQN	Discrete	Double · Dueling · PER · n-step · CNN
Value-based	C51	C51	Discrete	distributional (categorical) DQN
Value-based	QR-DQN	QRDQN	Discrete	distributional (quantile regression)
Value-based	Rainbow	Rainbow	Discrete	Double+Dueling+PER+n-step+C51+NoisyNets
Goal-conditioned	HER + DQN	HERDQN	Discrete (goal env)	hindsight goal relabeling for sparse rewards
Policy gradient	REINFORCE	REINFORCE	Discrete + Continuous	learned baseline
Actor-critic	A2C	A2C	Discrete + Continuous	GAE, vectorized
Actor-critic	PPO	PPO	Discrete + Continuous	clipped objective, GAE, KL early-stop
Actor-critic	TRPO	TRPO	Discrete + Continuous	KL trust region, conjugate-gradient natural step, line search
Actor-critic	GRPO	GRPO	Discrete + Continuous	critic-free, group-relative advantage (LLM-RLHF)
Actor-critic	IMPALA	IMPALA	Discrete + Continuous	V-trace, parallel actors
Actor-critic	Recurrent PPO	RecurrentPPO	Discrete	LSTM policy for partial observability
Actor-critic	SAC (discrete)	SACDiscrete	Discrete	max-entropy, auto temperature
Continuous	DDPG	DDPG	Continuous	deterministic policy, noise · PER · n-step
Continuous	TD3	TD3	Continuous	twin critics, delayed updates · PER · n-step
Continuous	SAC	SAC	Continuous	max-entropy, auto temperature · PER · n-step
Offline	TD3+BC	TD3BC	Continuous	learns from a fixed dataset (no env)
Offline	IQL	IQL	Continuous	expectile value + advantage-weighted policy
Offline	CQL	CQL	Continuous	conservative Q-learning (SAC backbone)
Offline	Decision Transformer	DecisionTransformer	Discrete + Continuous	return-conditioned sequence modeling (GPT)
Imitation	Diffusion Policy	DiffusionPolicy	Continuous	conditional denoising-diffusion policy (robotics)

See reproduced benchmark scores for all algorithms.

RLHF & LLM-style alignment

The same recipe that aligns language models, on control tasks: learn a reward from preferences, then optimize a policy against it with GRPO — the critic-free method behind modern LLM RLHF.

from decisionrl.envs import PointMass
from decisionrl.rlhf import collect_segments, synthetic_preferences, RewardModel, train_reward_model
from decisionrl.algorithms import SAC

env = PointMass()
segments = collect_segments(env, lambda o: env.action_space.sample(), n_segments=120, seg_len=25, seed=0)
prefs = synthetic_preferences(segments, n_pairs=800, seed=1)          # a preference teacher

reward_model = RewardModel(obs_dim=2, action_space=env.action_space, use_action=False)
train_reward_model(reward_model, prefs, n_iters=500)                  # Bradley-Terry likelihood
# -> learned reward correlates ≈0.98 with the true reward; optimize any agent on it:
from decisionrl.rlhf import RewardModelWrapper
agent = SAC(RewardModelWrapper(env, reward_model), seed=0).learn(20_000)

Or skip the reward model entirely with DPO (Direct Preference Optimization — the method behind modern LLM alignment), which optimizes the policy directly from preference pairs against a frozen reference:

from decisionrl.rlhf import DPO
dpo = DPO(PointMass(), beta=0.5, seed=0)
dpo.train(prefs, n_iters=600)     # no reward model, no RL loop
# learns the implicit reward directly — ≈0.9 held-out preference accuracy

decisionrl.rlhf provides RewardModel, PreferenceDataset, collect_segments, synthetic_preferences, train_reward_model, RewardModelWrapper and DPO.

Imitation learning

Learn from demonstrations instead of rewards — BC (behavioral cloning), DAgger (dataset aggregation, fixes BC's compounding error) and GAIL (adversarial imitation: a discriminator the policy learns to fool). BC and DAgger clone a CartPole expert to a perfect return of 500; GAIL matches it using only demonstrations and no environment reward.

from decisionrl.imitation import BC, GAIL, collect_expert_dataset
from decisionrl.envs import CartPole

demos = collect_expert_dataset(CartPole(), expert_policy, n_transitions=4000, seed=0)
bc = BC(CartPole(), seed=0); bc.train(demos, n_iters=1500)          # supervised cloning
gail = GAIL(CartPole(), demos, seed=0).learn(iterations=10)          # adversarial, reward-free

Or model the policy as a conditional denoising diffusion over actions (DiffusionPolicy, as in robotics) — it clones a PointMass expert to within noise of optimal and can represent multimodal action distributions a Gaussian cannot.

LLM alignment (RLHF on a language model)

The full RLHF loop industry uses to align LLMs, on a tiny char-level GPT: pre-train (SFT), then decisionrl toward a reward while a KL penalty keeps the policy close to the reference model (GRPO-style group-normalized advantages, no value network). Steering a model toward more "o" lifts its frequency from ≈0.09 to ≈0.47 while staying readable.

from decisionrl.text import CharTokenizer, CharGPT, sft_train, rlhf_finetune, char_frequency_reward

tok = CharTokenizer(corpus)
lm = CharGPT(tok.vocab_size, block_size=64)
sft_train(lm, tok, corpus, n_iters=2000)                       # supervised pre-training
rlhf_finetune(lm, tok, char_frequency_reward("o"), kl_coef=0.05)  # align to a reward + KL

Curiosity & return-conditioned control

# Intrinsic motivation: any agent gets exploration on sparse-reward tasks for free.
from decisionrl.exploration import RND, CuriosityWrapper
from decisionrl.algorithms import DQN
env = CuriosityWrapper(CartPole(), RND(obs_dim=4))      # or ICM(...)
DQN(env, seed=0).learn(50_000)

# Decision Transformer: offline RL as return-conditioned sequence modeling.
from decisionrl import collect_trajectories
from decisionrl.algorithms import DecisionTransformer
data = collect_trajectories(CartPole(), policy, n_trajectories=150, seed=0)
dt = DecisionTransformer(CartPole(), seed=0).learn_offline(data, n_iters=2500)
dt.evaluate(CartPole(), target_return=500)             # condition on the return you want

Evolutionary & swarm optimization

A full family of gradient-free optimizers under one ask/tell interface — evolution strategies CEM · CMA-ES · Differential Evolution · Genetic Algorithm · OpenAI-ES · ARS · Simulated Annealing and swarm intelligence PSO · Firefly · Artificial Bee Colony · Grey Wolf · Bat · Ant Colony (TSP) — plus a NeuroevolutionAgent that trains RL policies with any of them (no gradients).

from decisionrl.evolution import CEM, minimize
from decisionrl.evolution.functions import rastrigin
x, f, history = minimize(rastrigin, CEM(dim=10, bounds=(-5.12, 5.12), seed=0), iters=200)

# Neuroevolution: solve CartPole with a gradient-free optimizer
from decisionrl.evolution import NeuroevolutionAgent
from decisionrl.envs import CartPole
agent = NeuroevolutionAgent(CartPole(), optimizer="cmaes", seed=0).learn(60_000)

All twelve optimizers converge on the multimodal Rastrigin function (Grey Wolf reaches ~1e-9); every neuroevolution optimizer solves CartPole (return 500) with no gradients; and Ant Colony Optimization finds short TSP tours. Reproduce with python examples/evolution_demo.py.

AlphaZero (MCTS + self-play)

decisionrl.alphazero implements AlphaZero for two-player perfect-information games — Monte-Carlo Tree Search guided by a policy+value network, trained purely by self-play (no human games, no reward shaping). Ships TicTacToe and Connect4; add a game by implementing the Game interface.

from decisionrl.alphazero import AlphaZero, TicTacToe
agent = AlphaZero(TicTacToe(), n_simulations=60, seed=0)
agent.learn(iterations=12, games_per_iter=30)     # self-play + training
action = agent.predict(state, player=1)            # MCTS-backed move

Trained by self-play alone, it learns Tic-Tac-Toe to near-perfect play (stops losing to a random opponent). Reproduce with python examples/alphazero_demo.py.

Meta-RL (RL²)

decisionrl.meta implements RL² — meta-learning by training a recurrent policy across a distribution of tasks so its hidden state adapts online, with no gradient steps at test time. The mechanism is all in the environment: RL2Env feeds the previous action/reward/done alongside each observation and keeps one task alive for a whole "trial".

from decisionrl.algorithms import RecurrentPPO
from decisionrl.meta import make_meta_bandit
from decisionrl.wrappers import SyncVectorEnv

# a distribution of 5-armed Bernoulli bandits (arm odds resampled each trial)
venv = SyncVectorEnv([lambda i=i: make_meta_bandit(n_arms=5, horizon=30, seed=i)
                      for i in range(32)])
agent = RecurrentPPO(venv, n_steps=30, gae_lambda=0.3, seed=0).learn(500_000)

On held-out bandits the meta-trained policy explores then locks onto the best arm — pulling it far more often than chance — a bandit algorithm discovered by gradient descent. See docs.

Serving trained policies

Export any trained agent to ONNX (or TorchScript) and serve it over HTTP — the serving image needs only onnxruntime + FastAPI, no PyTorch.

from decisionrl.algorithms import PPO
from decisionrl.envs import CartPole
from decisionrl.serving import export_onnx, OnnxPolicy

agent = PPO(CartPole(), seed=0).learn(50_000)
export_onnx(agent, "policy.onnx")            # + policy.onnx.json metadata
action = OnnxPolicy("policy.onnx").predict(obs)   # inference without torch

# FastAPI service (POST /predict, GET /health, GET /info) — see deploy/Dockerfile
REINFORCE_MODEL=policy.onnx uvicorn decisionrl.serving.server:app

Store and reload pretrained policies with the model zoo, and run a policy entirely in the browser — examples/make_browser_demo.py writes a self-contained docs/demo/cartpole.html that plays CartPole with the trained network in pure JavaScript (no server, no CDN):

from decisionrl.zoo import save_to_zoo, load_pretrained, list_pretrained
save_to_zoo(agent, "cartpole-ppo")            # export to the zoo (ONNX)
policy = load_pretrained("cartpole-ppo")       # torch-free inference later

Multi-agent

from decisionrl.multiagent import MultiAgentPPO, RockPaperScissors, CoordinationGame

# self-play (one shared policy controls every agent)
selfplay = MultiAgentPPO(RockPaperScissors(), shared_policy=True, seed=0).learn(40_000)

# independent PPO (a separate policy per agent) on a cooperative game
ippo = MultiAgentPPO(CoordinationGame(), shared_policy=False, seed=0).learn(20_000)

decisionrl.multiagent adds a MultiAgentEnv interface, example games, and MultiAgentPPO (self-play or IPPO). See the multi-agent docs.

Distributed training

from decisionrl import DistributedActorLearner
from decisionrl.envs import CartPole

# real actor processes stream trajectories to a central V-trace learner
learner = DistributedActorLearner(CartPole, num_actors=8, seed=0).learn(200_000)

DistributedActorLearner is a true multi-process, IMPALA-style architecture: each actor runs its own environment and local policy inference in a separate process, and the learner performs V-trace updates and broadcasts fresh weights every iteration.

Components you can reuse

decisionrl
├── core         # Env, Wrapper, Space (Box/Discrete), BaseAgent, Transition
├── envs         # applied: Inventory, DynamicPricing, QueueAdmissionControl,
│                 #   EnergyMicrogrid, SupplyChain, Thermostat;
│                 #   control: GridWorld, CartPole, Pendulum, PointMass; make_gym
├── buffers      # ReplayBuffer, PrioritizedReplayBuffer (sum-tree), RolloutBuffer (GAE)
├── networks     # build_mlp, QNetwork, Dueling/CategoricalQNetwork (C51),
│                 #   CNNFeatureExtractor + ImageQNetwork (pixels),
│                 #   Categorical/Gaussian/Squashed policies
├── exploration  # Linear/Exponential schedules, Gaussian & Ornstein-Uhlenbeck noise
├── wrappers     # TimeLimit, NormalizeObservation, NormalizeReward,
│                 #   SyncVectorEnv, AsyncVectorEnv (multiprocessing),
│                 #   FrameStack, FlattenObservation, OneHotObservation
├── utils        # set_seed, Logger (stdout/CSV/TensorBoard), RunningMeanStd, torch helpers
├── training     # evaluate_policy, Callback, EvalCallback, StopOnRewardThreshold
└── algorithms   # all 31 agents above

Everything is duck-typed against the Gymnasium API, so decisionrl components and Gymnasium environments interoperate freely in either direction.

Reproducibility

from decisionrl.utils import set_seed
set_seed(42, deterministic=True)   # seeds Python, NumPy, PyTorch (+ deterministic kernels)

Every agent accepts a seed= argument, every environment accepts reset(seed=...), and every buffer/space has its own seedable RNG.

Development & testing

pip install -e ".[dev]"
pytest              # full suite (unit + integration "does it actually learn?" tests)
ruff check .        # lint

The test suite covers component correctness (spaces, buffers, sum-tree, schedules, GAE, normalization, save/load round-trips) and learning behaviour: tabular methods reach the optimal policy on GridWorld, DQN/PPO learn CartPole, and SAC/TD3/DDPG solve the PointMass reaching task.

Design notes

• terminated vs truncated. Off-policy buffers store the terminated flag only, so bootstrapping targets are correct on time-limit truncation. On-policy rollouts augment the reward with gamma * V(final_obs) at truncated steps and mark the episode boundary — the Stable-Baselines3 approach.
• No hidden global state. No registries, no config magic; you construct objects and call methods.
• Small surface, deep correctness. The goal is a foundation you can read in an afternoon and trust in a paper.

License

MIT © 2026 Denis Drobyshev

Acknowledgements

Inspired by the clarity of CleanRL, the API design of Stable-Baselines3, the modularity of Tianshou, and the Farama Foundation's Gymnasium standard.