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  {
   "cell_type": "markdown",
   "id": "801ebbba",
   "metadata": {},
   "source": [
    "# Log messages\n",
    "\n",
    "[![Click and Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/metadriverse/metadrive/blob/main/documentation/source/log_msg.ipynb)\n",
    "\n",
    "\n",
    "Logging message is important to oversee the program status. MetaDrive adopts Python's `logging` module to log messages. "
   ]
  },
  {
   "cell_type": "markdown",
   "id": "443f8317",
   "metadata": {},
   "source": [
    "## Global logger \n",
    "We provide a wrapper in `metadrive/engine/logger` to customize some features. We recommend using it to log messages to make the logging consistent. It is a global variable, so you can get the logger at anywhere of your code. Some classes like `BaseEnv` may have a variable called `logger` as well, which is actually the same as the global logger."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a08dffbc",
   "metadata": {},
   "outputs": [],
   "source": [
    "from metadrive.envs.base_env import BaseEnv\n",
    "from metadrive.engine.logger import get_logger # get_logger\n",
    "\n",
    "logger = get_logger()\n",
    "\n",
    "# create environment\n",
    "logger.info(\"Create environment\\n\")\n",
    "env = BaseEnv(dict(use_render=False))\n",
    "assert logger is env.logger # the environment.logger is the same as global logger\n",
    "\n",
    "# reset environment\n",
    "logger.info(\"Reset environment\")\n",
    "env.reset()\n",
    "try:\n",
    "    for i in range(5):\n",
    "        logger.info(\"Simulate step {}\".format(i))\n",
    "        env.step(env.action_space.sample())\n",
    "finally:\n",
    "    logger.info(\"Close environment\")\n",
    "    env.close()\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a8f87467",
   "metadata": {},
   "source": [
    "The logger can be used at everywhere. For example, it can be used in your manager."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "39443673",
   "metadata": {},
   "outputs": [],
   "source": [
    "from metadrive.envs.base_env import BaseEnv\n",
    "from metadrive.engine.logger import get_logger # get_logger\n",
    "from metadrive.manager.base_manager import BaseManager\n",
    "\n",
    "logger = get_logger()\n",
    "\n",
    "class MyMgr(BaseManager):\n",
    "    \n",
    "    def __init__(self):\n",
    "        super(MyMgr, self).__init__()\n",
    "        logger.info(\"Init MyMgr...\")\n",
    "    \n",
    "    def after_step(self, *args, **kwargs):\n",
    "        logger.info(\"Step {}...\".format(self.episode_step))\n",
    "        return dict()\n",
    "\n",
    "\n",
    "# create environment\n",
    "env = BaseEnv(dict(use_render=False))\n",
    "\n",
    "# reset environment\n",
    "env.reset()\n",
    "\n",
    "# add manager\n",
    "env.engine.register_manager(\"my_mgr\", MyMgr())\n",
    "try:\n",
    "    for i in range(5):\n",
    "        env.step(env.action_space.sample())\n",
    "finally:\n",
    "    env.close()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "98b765f0",
   "metadata": {},
   "source": [
    "## Log level\n",
    "Similar to `logging` module, one can change the log level to decide which log messages to be printed. Generally, MetaDrive uses `logging.INFO`, `logging.DEBUG`, and `logging.WARNING` to classify log messages. By default, the log level is `logging.INFO` and thus debug messages will be hidden. The log level can be set in environment config. The following example shows how to print more debug message by setting `log_level=logging.DEBUG`. In addition, if `debug=True` in the environment config, the log level will be set to `logging.DEBUG` as well. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "0c77a550",
   "metadata": {},
   "outputs": [],
   "source": [
    "from metadrive.envs.base_env import BaseEnv\n",
    "import logging\n",
    "from metadrive.engine.logger import get_logger # get_logger\n",
    "\n",
    "logger = get_logger()\n",
    "\n",
    "# create environment\n",
    "env = BaseEnv(dict(use_render=False, log_level=logging.DEBUG))\n",
    "assert logger is env.logger # the environment.logger is the same as global logger\n",
    "\n",
    "# reset environment\n",
    "logger.debug(\"Reset environment\")\n",
    "env.reset()\n",
    "try:\n",
    "    for i in range(5):\n",
    "        logger.debug(\"Simulate step {}\".format(i))\n",
    "        env.step(env.action_space.sample())\n",
    "finally:\n",
    "    logger.debug(\"Close environment\")\n",
    "    env.close()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "312cc6dc",
   "metadata": {},
   "source": [
    "If you would like to turn off all log messages, changing the log_level to `logging.WARNING` (or `logging.CRITICAL`) can suppress messages logged by `logging.info()`, `logging.debug()` (or even `logging.warn`)."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "ed56a0c4",
   "metadata": {},
   "outputs": [],
   "source": [
    "from metadrive.engine.logger import set_log_level # get_logger\n",
    "\n",
    "def run(): # define the simulation loop\n",
    "    # reset environment\n",
    "    logger.debug(\"Reset environment\")\n",
    "    env.reset()\n",
    "    try:\n",
    "        for i in range(5):\n",
    "            logger.debug(\"Simulate step {}\".format(i))\n",
    "            env.step(env.action_space.sample())\n",
    "    finally:\n",
    "        logger.debug(\"Close environment\")\n",
    "        env.close()\n",
    "\n",
    "set_log_level(logging.WARNING) # Or set it in environment config\n",
    "run()\n",
    "\n",
    "\n",
    "print(\"Turn off all messages...\")    \n",
    "\n",
    "set_log_level(logging.CRITICAL) # Or set it in environment config\n",
    "run()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "3c3e6834",
   "metadata": {},
   "source": [
    "## Log once\n",
    "Sometimes, we may want the message to be logged only once in one episode. In this case, we can use the `log_once` key to notify the logger to show some messages only once until the next `reset` is called."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "28b15685",
   "metadata": {},
   "outputs": [],
   "source": [
    "from metadrive.envs.base_env import BaseEnv\n",
    "import logging\n",
    "\n",
    "# create environment\n",
    "env = BaseEnv(dict(use_render=False, log_level=logging.CRITICAL))\n",
    "\n",
    "# reset environment\n",
    "env.reset()\n",
    "try:\n",
    "    for i in range(5):\n",
    "        env.logger.critical(\"Step... (I will only show once)\".format(i), extra={\"log_once\": True})\n",
    "        env.step(env.action_space.sample())\n",
    "finally:\n",
    "    env.close()\n"
   ]
  }
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