02-python-essentials/02.20-warnings.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# 警告"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "出现了一些需要让用户知道的问题，但又不想停止程序，这时候我们可以使用警告：\n",
    "\n",
    "首先导入警告模块："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "import warnings"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "在需要的地方，我们使用 `warnings` 中的 `warn` 函数：\n",
    "\n",
    "    warn(msg, WarningType = UserWarning)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "c:\\Anaconda\\lib\\site-packages\\IPython\\kernel\\__main__.py:4: RuntimeWarning: month (13) is not between 1 and 12\n"
     ]
    }
   ],
   "source": [
    "def month_warning(m):\n",
    "    if not 1<= m <= 12:\n",
    "        msg = \"month (%d) is not between 1 and 12\" % m\n",
    "        warnings.warn(msg, RuntimeWarning)\n",
    "\n",
    "month_warning(13)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "有时候我们想要忽略特定类型的警告，可以使用 `warnings` 的 `filterwarnings` 函数：\n",
    "\n",
    "    filterwarnings(action, category)\n",
    "\n",
    "将 `action` 设置为 `'ignore'` 便可以忽略特定类型的警告："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "warnings.filterwarnings(action = 'ignore', category = RuntimeWarning)\n",
    "\n",
    "month_warning(13)"
   ]
  }
 ],
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