Chapter_1.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 实现一摞纸牌"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [],
   "source": [
    "import collections"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "Card = collections.namedtuple('Card', ['rank', 'suit'])\n",
    "\n",
    "class FrenchDeck:\n",
    "    ranks = [str(n) for n in range(2, 11)] + list('JQKA')  #面值\n",
    "    suits = 'spades diamonds clubs hearts'.split()         #花色\n",
    "    \n",
    "    def __init__(self):\n",
    "        self._cards = [Card(rank, suit) for suit in self.suits for rank in self.ranks] #定义了不同花色不同面值的52张牌\n",
    "    def __len__(self):\n",
    "        return len(self._cards)\n",
    "    def __getitem__(self, position):\n",
    "        return self._cards[position]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "52"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "deck = FrenchDeck()\n",
    "len(deck)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Card(rank='2', suit='spades')\n",
      "Card(rank='A', suit='hearts')\n"
     ]
    }
   ],
   "source": [
    "print(deck[0])\n",
    "print(deck[-1])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Card(rank='7', suit='spades')\n",
      "Card(rank='6', suit='hearts')\n",
      "Card(rank='7', suit='spades')\n",
      "Card(rank='2', suit='clubs')\n",
      "Card(rank='6', suit='clubs')\n"
     ]
    }
   ],
   "source": [
    "from random import choice \n",
    "for _ in range(5):\n",
    "    print(choice(deck))  #随机抽牌"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [],
   "source": [
    "# 2最小，A最大；黑桃最大，红桃次之，方块再次，梅花最小\n",
    "suit_values = dict(spades=3, hearts=2, diamonds=1, clubs=0)\n",
    "\n",
    "def spades_high(card):\n",
    "    rank_value = FrenchDeck.ranks.index(card.rank)   #这一句不太理解？？\n",
    "    return rank_value * len(suit_values) + suit_values[card.suit]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Card(rank='2', suit='clubs')\n",
      "Card(rank='2', suit='diamonds')\n",
      "Card(rank='2', suit='hearts')\n",
      "Card(rank='2', suit='spades')\n",
      "Card(rank='3', suit='clubs')\n",
      "Card(rank='3', suit='diamonds')\n",
      "Card(rank='3', suit='hearts')\n",
      "Card(rank='3', suit='spades')\n",
      "Card(rank='4', suit='clubs')\n",
      "Card(rank='4', suit='diamonds')\n",
      "Card(rank='4', suit='hearts')\n",
      "Card(rank='4', suit='spades')\n",
      "Card(rank='5', suit='clubs')\n",
      "Card(rank='5', suit='diamonds')\n",
      "Card(rank='5', suit='hearts')\n",
      "Card(rank='5', suit='spades')\n",
      "Card(rank='6', suit='clubs')\n",
      "Card(rank='6', suit='diamonds')\n",
      "Card(rank='6', suit='hearts')\n",
      "Card(rank='6', suit='spades')\n",
      "Card(rank='7', suit='clubs')\n",
      "Card(rank='7', suit='diamonds')\n",
      "Card(rank='7', suit='hearts')\n",
      "Card(rank='7', suit='spades')\n",
      "Card(rank='8', suit='clubs')\n",
      "Card(rank='8', suit='diamonds')\n",
      "Card(rank='8', suit='hearts')\n",
      "Card(rank='8', suit='spades')\n",
      "Card(rank='9', suit='clubs')\n",
      "Card(rank='9', suit='diamonds')\n",
      "Card(rank='9', suit='hearts')\n",
      "Card(rank='9', suit='spades')\n",
      "Card(rank='10', suit='clubs')\n",
      "Card(rank='10', suit='diamonds')\n",
      "Card(rank='10', suit='hearts')\n",
      "Card(rank='10', suit='spades')\n",
      "Card(rank='J', suit='clubs')\n",
      "Card(rank='J', suit='diamonds')\n",
      "Card(rank='J', suit='hearts')\n",
      "Card(rank='J', suit='spades')\n",
      "Card(rank='Q', suit='clubs')\n",
      "Card(rank='Q', suit='diamonds')\n",
      "Card(rank='Q', suit='hearts')\n",
      "Card(rank='Q', suit='spades')\n",
      "Card(rank='K', suit='clubs')\n",
      "Card(rank='K', suit='diamonds')\n",
      "Card(rank='K', suit='hearts')\n",
      "Card(rank='K', suit='spades')\n",
      "Card(rank='A', suit='clubs')\n",
      "Card(rank='A', suit='diamonds')\n",
      "Card(rank='A', suit='hearts')\n",
      "Card(rank='A', suit='spades')\n"
     ]
    }
   ],
   "source": [
    "for card in sorted(deck, key=spades_high):\n",
    "    print(card)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "\n",
    "\n",
    "## 实现一个简单的二维向量类"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 39,
   "metadata": {},
   "outputs": [],
   "source": [
    "from math import hypot\n",
    "\n",
    "class Vector:\n",
    "    \n",
    "    def __init__(self, x=0, y=0):\n",
    "        self.x = x\n",
    "        self.y = y\n",
    "\n",
    "    def __repr__(self):\n",
    "        return 'Vector(%r, %r)' % (self.x, self.y)\n",
    "    \n",
    "    def __abs__(self):\n",
    "        return hypot(self.x, self.y) #返回模值\n",
    "    \n",
    "    def __bool__(self):\n",
    "        return bool(abs(self))\n",
    "    \n",
    "    def __add__(self, other):\n",
    "        x = self.x + other.x\n",
    "        y = self.y + other.y\n",
    "        return Vector(x, y)\n",
    "    \n",
    "    def __mul__(self, scalar):\n",
    "        return Vector(self.x * scalar, self.y * scalar)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 40,
   "metadata": {},
   "outputs": [],
   "source": [
    "a = Vector(3, 4)\n",
    "b = Vector(5, 12)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 41,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Vector(3, 4)"
      ]
     },
     "execution_count": 41,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a     #实现了__repr__函数才会正常显示，否则会出现类似 <__main__.Vector at 0x1126964e0> 的情况"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 42,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Vector(8, 16)"
      ]
     },
     "execution_count": 42,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a + b"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Vector(30, 40)"
      ]
     },
     "execution_count": 44,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "a * 10"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "默认情况下，自定义的类总是为真。\n",
    "bool(x)的背后是调用x.__bool__()的结果，若该方法未实现则尝试调用x.__len()__。若返回0，则bool返回False; 否则返回True"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "bool(c): False\n",
      "bool(a): True\n"
     ]
    }
   ],
   "source": [
    "c = Vector()\n",
    "print('bool(c):', bool(c))\n",
    "print('bool(a):', bool(a))"
   ]
  }
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