{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Stable-Baselines3 快速上手：几行代码训练 PPO（CartPole-v1）。\n",
    "\n",
    "依赖：pip install stable-baselines3\n",
    "\n",
    "配套教程：[开源库](https://dqn.cn/resources/libraries)（DQN.CN 强化学习中文教程）\n",
    "\n",
    "源码：`examples/resources/sb3_quickstart.py`，本 notebook 由 `scripts/build-notebooks.mjs` 自动生成，代码与 .py 文件一致。代码默认在 CPU 上运行，固定了随机种子；部分脚本支持设置环境变量 `DQN_QUICK=1` 只跑很短的版本（见下一个单元）。"
   ],
   "id": "resources-sb3_quickstart-py-0"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 环境准备：在 Colab 等缺少依赖的环境中自动安装（本地已装好依赖时什么也不做）\n",
    "import importlib.util, os, subprocess, sys\n",
    "_need = [m for m in [\"gymnasium\",\"stable_baselines3\"] if importlib.util.find_spec(m) is None]\n",
    "if _need or \"google.colab\" in sys.modules:\n",
    "    subprocess.run([sys.executable, \"-m\", \"pip\", \"install\", \"-q\", \"gymnasium>=1.0\", \"stable-baselines3\"], check=True)\n",
    "sys.argv = sys.argv[:1]   # notebook 内核会带上 -f 等参数，清掉以免脚本把它们当成命令行参数\n",
    "# os.environ[\"DQN_QUICK\"] = \"1\"   # 取消注释：支持该开关的脚本只跑很短的版本，用于快速检查"
   ],
   "id": "resources-sb3_quickstart-py-1"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import gymnasium as gym\n",
    "from stable_baselines3 import PPO\n",
    "from stable_baselines3.common.evaluation import evaluate_policy\n",
    "\n",
    "env = gym.make(\"CartPole-v1\")\n",
    "model = PPO(\"MlpPolicy\", env, seed=0, verbose=0)\n",
    "model.learn(total_timesteps=50_000)\n",
    "\n",
    "mean_reward, std_reward = evaluate_policy(model, env, n_eval_episodes=10, deterministic=True)\n",
    "print(f\"PPO（SB3 默认超参数，5 万步）评估回报: {mean_reward:.1f} ± {std_reward:.1f}\")\n",
    "model.save(\"ppo_cartpole\")          # 保存模型，之后可用 PPO.load(\"ppo_cartpole\") 加载"
   ],
   "id": "resources-sb3_quickstart-py-2"
  }
 ],
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  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
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  "language_info": {
   "name": "python"
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  "colab": {
   "provenance": []
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 "nbformat": 4,
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