{ "cells": [ { "cell_type": "code", "execution_count": 11, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3, 4}" ] }, "execution_count": 11, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s = {1, 2, 3}\t\t\t\t#创建集合并赋值\n", "s.add(4)\t\t\t\t#添加元素\n", "s" ] }, { "cell_type": "code", "execution_count": 12, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3, 4, 5, 6}" ] }, "execution_count": 12, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s.update({4, 5, 6})\t\t\t#更新当前集合，自动忽略重复元素\n", "s\t\t\t\t\t#输出集合" ] }, { "cell_type": "code", "execution_count": 16, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3, 4, 6}" ] }, "execution_count": 16, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s.discard(5)\t\t\t\t#删除元素，不存在则忽略该操作\n", "s\t\t\t\t\t#输出集合" ] }, { "cell_type": "code", "execution_count": 14, "metadata": {}, "outputs": [ { "ename": "KeyError", "evalue": "5", "output_type": "error", "traceback": [ "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m", "\u001b[1;31mKeyError\u001b[0m Traceback (most recent call last)", "\u001b[1;32m\u001b[0m in \u001b[0;36m\u001b[1;34m()\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[0ms\u001b[0m\u001b[1;33m.\u001b[0m\u001b[0mremove\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;36m5\u001b[0m\u001b[1;33m)\u001b[0m \u001b[1;31m#删除元素，不存在则抛出异常\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m", "\u001b[1;31mKeyError\u001b[0m: 5" ] } ], "source": [ "s.remove(5)\t\t\t\t#删除元素，不存在则抛出异常" ] }, { "cell_type": "code", "execution_count": 23, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "{1, 3, 4, 5}\n" ] }, { "data": { "text/plain": [ "1" ] }, "execution_count": 23, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s= {4,3,5,1}\n", "print(s)\n", "s.pop()\t" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "s" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# dict简单介绍
\n", "Python内置了字典：dict的支持，dict全称dictionary，在其他语言中也称为map，使用键-值（key-value）存储，具有极快的查找速度。\n", "\n", "理解字典后，你就能够更准确地为各种真实物体建模。你可以创建一个表示人的字典，然后想在其中存储多少信息就存储多少信息：
\n", "姓名、年龄、地址、职业以及要描述的任何方面。你还能够存储任意两种相关的信息，如一系列单词及其含义，一系列人名及其喜欢的数
\n", "字，以及一系列山脉及其海拔等。\n", "\n", "举个例子，假设要根据同学的名字查找对应的成绩，如果用list实现，需要两个list：" ] }, { "cell_type": "code", "execution_count": 50, "metadata": {}, "outputs": [], "source": [ "names = ['Michael', 'Bob', 'Tracy']\n", "scores = [95, 75, 85]" ] }, { "cell_type": "code", "execution_count": 1, "metadata": {}, "outputs": [], "source": [ "d = {'Michael': 95, 'Bob': 75, 'Tracy': 85}" ] }, { "cell_type": "code", "execution_count": 2, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'Michael': 95, 'Bob': 75, 'Tracy': 85}" ] }, "execution_count": 2, "metadata": {}, "output_type": "execute_result" } ], "source": [ "d" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "key-value存储方式，在放进去的时候，必须根据key算出value的存放位置，这样，取的时候才能根据key直接拿到value。
\n", "\n", "把数据放入dict的方法，除了初始化时指定外，还可以通过key放入：" ] }, { "cell_type": "code", "execution_count": 3, "metadata": {}, "outputs": [], "source": [ "d['Adam'] = 67" ] }, { "cell_type": "code", "execution_count": 4, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'Michael': 95, 'Bob': 75, 'Tracy': 85, 'Adam': 67}" ] }, "execution_count": 4, "metadata": {}, "output_type": "execute_result" } ], "source": [ "d" ] }, { "cell_type": "code", "execution_count": 5, "metadata": {}, "outputs": [], "source": [ "d['Adam'] = 90" ] }, { "cell_type": "code", "execution_count": 6, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'Michael': 95, 'Bob': 75, 'Tracy': 85, 'Adam': 90}" ] }, "execution_count": 6, "metadata": {}, "output_type": "execute_result" } ], "source": [ "d" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "如果key不存在，dict就会报错：" ] }, { "cell_type": "code", "execution_count": 7, "metadata": {}, "outputs": [ { "ename": "KeyError", "evalue": "'aa'", "output_type": "error", "traceback": [ "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m", "\u001b[1;31mKeyError\u001b[0m Traceback (most recent call last)", "\u001b[1;32m\u001b[0m in \u001b[0;36m\u001b[1;34m\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[0md\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;34m'aa'\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m", "\u001b[1;31mKeyError\u001b[0m: 'aa'" ] } ], "source": [ "d['aa']" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "要避免key不存在的错误，有两种办法
\n", "**第一种：**是通过in判断key是否存在：" ] }, { "cell_type": "code", "execution_count": 8, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "True" ] }, "execution_count": 8, "metadata": {}, "output_type": "execute_result" } ], "source": [ "# 'Thomas' in d\n", "'Adam' in d" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**第二种：**是通过dict提供的get()方法，如果key不存在，可以返回None，或者自己指定的value：
\n", "返回None的时候Python的交互环境不显示结果。" ] }, { "cell_type": "code", "execution_count": 9, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "90" ] }, "execution_count": 9, "metadata": {}, "output_type": "execute_result" } ], "source": [ "d.get('Adam',-1)" ] }, { "cell_type": "code", "execution_count": 10, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "'XXXXXXXXXXXXXXXXXXXXXXXXXXX'" ] }, "execution_count": 10, "metadata": {}, "output_type": "execute_result" } ], "source": [ "d.get('Thomas', 'XXXXXXXXXXXXXXXXXXXXXXXXXXX')" ] }, { "cell_type": "code", "execution_count": 11, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'Michael': 95, 'Bob': 75, 'Tracy': 85, 'Adam': 90}" ] }, "execution_count": 11, "metadata": {}, "output_type": "execute_result" } ], "source": [ "d" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**删除一个key**，用**pop(key)**方法，对应的value也会从dict中删除：" ] }, { "cell_type": "code", "execution_count": 12, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'Michael': 95, 'Tracy': 85, 'Adam': 90}" ] }, "execution_count": 12, "metadata": {}, "output_type": "execute_result" } ], "source": [ "d.pop('Bob')\n", "d" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "dict内部存放的顺序和key放入的顺序是没有关系的。" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# 和list比较，dict有以下几个特点：\n", "\n", "1.查找和插入的速度极快，不会随着key的增加而变慢；
\n", "2.需要占用大量的内存，内存浪费多。
\n", "**list：**
\n", "1.查找和插入的时间随着元素的增加而增加；
\n", "2.占用空间小，浪费内存很少。
\n", "所以，dict是用空间来换取时间的一种方法。" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "dict适合用于高速查找的地方，**dict的key必须是不可变对象**。
\n", "这是因为dict根据key来计算value的存储位置，如果每次计算相同的key得出的结果不同，那dict内部就完全混乱了。" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "通过key计算位置的算法称为哈希算法（Hash）。**要保证hash的正确性，作为key的对象就不能变。**\n", "在Python中，**字符串、整数等**都是不可变的，因此，可以放心地作为key。**list是可变的，就不能作为key:**" ] }, { "cell_type": "code", "execution_count": 15, "metadata": {}, "outputs": [ { "ename": "TypeError", "evalue": "unhashable type: 'list'", "output_type": "error", "traceback": [ "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m", "\u001b[1;31mTypeError\u001b[0m Traceback (most recent call last)", "\u001b[1;32m\u001b[0m in \u001b[0;36m\u001b[1;34m()\u001b[0m\n\u001b[0;32m 1\u001b[0m \u001b[0mkey\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;33m[\u001b[0m\u001b[1;36m1\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;36m2\u001b[0m\u001b[1;33m,\u001b[0m \u001b[1;36m3\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 2\u001b[1;33m \u001b[0md\u001b[0m\u001b[1;33m[\u001b[0m\u001b[0mkey\u001b[0m\u001b[1;33m]\u001b[0m \u001b[1;33m=\u001b[0m \u001b[1;34m'a list'\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m 3\u001b[0m \u001b[0md\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n", "\u001b[1;31mTypeError\u001b[0m: unhashable type: 'list'" ] } ], "source": [ "key = [1, 2, 3]\n", "d[key] = 'a list'\n", "d" ] }, { "cell_type": "code", "execution_count": 16, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'Michael': 95, 'Tracy': 85, 'Adam': 90, 1: 'number'}" ] }, "execution_count": 16, "metadata": {}, "output_type": "execute_result" } ], "source": [ "key=1\n", "d[key]='number'\n", "d" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**1 访问字典中的值**" ] }, { "cell_type": "code", "execution_count": 13, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "You just earned 5 points!\n" ] } ], "source": [ "alien_0 = {'color': 'green', 'points': 5}\n", "new_points = alien_0['points']\n", "print(\"You just earned \" + str(new_points) + \" points!\")" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**2 添加键—值对**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "字典是一种动态结构，可随时在其中添加键—值对。 要添加键—值对，可依次指定字典名、
用\n", "方括号括起的键和相关联的值。" ] }, { "cell_type": "code", "execution_count": 14, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "{'color': 'green', 'points': 5}\n", "{'color': 'green', 'points': 5, 'x_position': 0, 'y_position': 25}\n" ] } ], "source": [ "alien_0 = {'color': 'green', 'points': 5}\n", "print(alien_0)\n", "alien_0['x_position'] = 0\n", "alien_0['y_position'] = 25\n", "print(alien_0)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**3 创建空字典**" ] }, { "cell_type": "code", "execution_count": 15, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'color': 'green', 'points': 5}" ] }, "execution_count": 15, "metadata": {}, "output_type": "execute_result" } ], "source": [ "alien_0 = {}\n", "alien_0['color'] = 'green'\n", "alien_0['points'] = 5\n", "alien_0 " ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**4 修改字典中的值**" ] }, { "cell_type": "code", "execution_count": 16, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "The alien is green.\n", "The alien is now yellow.\n" ] } ], "source": [ "alien_0 = {'color': 'green'}\n", "print(\"The alien is \" + alien_0['color'] + \".\")\n", "alien_0['color'] = 'yellow'\n", "print(\"The alien is now \" + alien_0['color'] + \".\")" ] }, { "cell_type": "code", "execution_count": 20, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Original x-position: 0\n" ] } ], "source": [ "alien_0 = {'x_position': 0, 'y_position': 25, 'speed': 'medium'}\n", "print(\"Original x-position: \" + str(alien_0['x_position']))" ] }, { "cell_type": "code", "execution_count": 23, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "New x-position: 5\n" ] } ], "source": [ "# 向右移动外星人\n", "# 据外星人当前速度决定将其移动多远\n", "if alien_0['speed'] == 'slow':\n", " x_increment = 1\n", "elif alien_0['speed'] == 'medium':\n", " x_increment = 2\n", "else:\n", " # 这个外星人的速度一定很快\n", " x_increment = 3\n", "# 新位置等于老位置加上增量\n", "alien_0['x_position'] = alien_0['x_position'] + x_increment\n", "print(\"New x-position: \" + str(alien_0['x_position']))" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "这种技术很棒
例如，要将这个速度中\n", "等的外星人变成速度很快的外星人，可添加如下代码行：" ] }, { "cell_type": "code", "execution_count": 22, "metadata": {}, "outputs": [], "source": [ "alien_0['speed'] = 'fast'" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**5 删除键— 值对**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "对于字典中不再需要的信息，可使用del语句将相应的键—值对彻底删除。使用del语句时，
\n", "必须指定字典名和要删除的键。\n", "例如，下面的代码从字典alien_0中删除键'points'及其值：" ] }, { "cell_type": "code", "execution_count": 21, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "{'color': 'green', 'points': 5}\n", "{'color': 'green'}\n" ] } ], "source": [ "alien_0 = {'color': 'green', 'points': 5}\n", "print(alien_0)\n", "del alien_0['points']\n", "print(alien_0)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**6 由类似对象组成的字典**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "在前面的示例中，字典存储的是一个对象（游戏中的一个外星人）的多种信息，但你也可以
\n", "使用字典来存储众多对象的同一种信息。例如，假设你要调查很多人，询问他们最喜欢的编程语
\n", "言，可使用一个字典来存储这种简单调查的结果，如下所示：" ] }, { "cell_type": "code", "execution_count": 22, "metadata": {}, "outputs": [], "source": [ "favorite_languages = {\n", "'jen': 'python',\n", "'sarah': 'c',\n", "'edward': 'ruby',\n", "'phil': 'python',\n", "}" ] }, { "cell_type": "code", "execution_count": 23, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Sarah's favorite language is C.\n" ] } ], "source": [ "print(\"Sarah's favorite language is \" + \n", " favorite_languages['sarah'].title() + \".\")" ] }, { "cell_type": "code", "execution_count": 24, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "'c'" ] }, "execution_count": 24, "metadata": {}, "output_type": "execute_result" } ], "source": [ "favorite_languages['sarah']" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "markdown", "metadata": {}, "source": [ " # 遍历字典" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "一个Python字典可能只包含几个键—值对，也可能包含数百万个键—值对。 鉴于字典可能包含
\n", "大量的数据， Python支持对字典遍历。字典可用于以各种方式存储信息，因此有多种遍历字典的
\n", "方式：可遍历字典的所有键—值对、键或值。" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**1 遍历所有的键— 值对**" ] }, { "cell_type": "code", "execution_count": 17, "metadata": {}, "outputs": [], "source": [ "user_0 = {\n", "'username': 'efermi',\n", "'first': 'enrico',\n", "'last': 'fermi',\n", "}" ] }, { "cell_type": "code", "execution_count": 17, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "dict_items([('username', 'efermi'), ('first', 'enrico'), ('last', 'fermi')])" ] }, "execution_count": 17, "metadata": {}, "output_type": "execute_result" } ], "source": [ "user_0.items()" ] }, { "cell_type": "code", "execution_count": 18, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", "Key: username\n", "Value: efermi\n", "\n", "Key: first\n", "Value: enrico\n", "\n", "Key: last\n", "Value: fermi\n" ] } ], "source": [ "# 从字典中同时取两个值\n", "for key,value in user_0.items():\n", " print(\"\\nKey: \" + key)\n", " print(\"Value: \" + value)" ] }, { "cell_type": "code", "execution_count": 19, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "dict_items([('username', 'efermi'), ('first', 'enrico'), ('last', 'fermi')])" ] }, "execution_count": 19, "metadata": {}, "output_type": "execute_result" } ], "source": [ "user_0.items()" ] }, { "cell_type": "code", "execution_count": 19, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Jen's favorite language is Python.\n", "Sarah's favorite language is C.\n", "Edward's favorite language is Ruby.\n", "Phil's favorite language is Python.\n" ] } ], "source": [ "favorite_languages = {\n", "'jen': 'python',\n", "'sarah': 'c',\n", "'edward': 'ruby',\n", "'phil': 'python',\n", "}\n", "for name, language in favorite_languages.items():\n", " print(name.title() + \"'s favorite language is \" + language.title() + \".\")" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**2 遍历字典中的所有键**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "在不需要使用字典中的值时，方法keys()很有用。下面来遍历字典favorite_languages，
并\n", "将每个被调查者的名字都打印出来：" ] }, { "cell_type": "code", "execution_count": 21, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Jen Sarah Edward Phil " ] } ], "source": [ "favorite_languages = {\n", "'jen': 'python',\n", "'sarah': 'c',\n", "'edward': 'ruby',\n", "'phil': 'python',\n", "}\n", "for name in favorite_languages.keys():\n", " print(name.title(),end = ' ')" ] }, { "cell_type": "code", "execution_count": 22, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "dict_keys(['jen', 'sarah', 'edward', 'phil'])" ] }, "execution_count": 22, "metadata": {}, "output_type": "execute_result" } ], "source": [ "favorite_languages.keys()" ] }, { "cell_type": "code", "execution_count": 23, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "dict_values(['python', 'c', 'ruby', 'python'])" ] }, "execution_count": 23, "metadata": {}, "output_type": "execute_result" } ], "source": [ "favorite_languages.values()" ] }, { "cell_type": "code", "execution_count": 24, "metadata": {}, "outputs": [], "source": [ "favorite_languages['aa']='python'" ] }, { "cell_type": "code", "execution_count": 25, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'jen': 'python',\n", " 'sarah': 'c',\n", " 'edward': 'ruby',\n", " 'phil': 'python',\n", " 'aa': 'python'}" ] }, "execution_count": 25, "metadata": {}, "output_type": "execute_result" } ], "source": [ "favorite_languages" ] }, { "cell_type": "code", "execution_count": 28, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "('aa', 'python')" ] }, "execution_count": 28, "metadata": {}, "output_type": "execute_result" } ], "source": [ "# favorite_languages.popitem(key=='aa')\n", "favorite_languages.popitem()" ] }, { "cell_type": "code", "execution_count": 29, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{'jen': 'python', 'sarah': 'c', 'edward': 'ruby', 'phil': 'python'}" ] }, "execution_count": 29, "metadata": {}, "output_type": "execute_result" } ], "source": [ "favorite_languages" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "markdown", "metadata": {}, "source": [ "下面来打印两条消息，指出两位朋友喜欢的语言。
\n", "我们像前面一样遍历字典中的名字，但在名字为指定朋友的名字时，
打印一条消息，\n", "指出其喜欢的语言：" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "favorite_languages = {\n", "'jen': 'python',\n", "'sarah': 'c',\n", "'edward': 'ruby',\n", "'phil': 'python',\n", "}\n", "friends = ['phil', 'sarah']\n", "for name in favorite_languages.keys():\n", " print(name.title())\n", " if name in friends:\n", " print(\" Hi \" + name.title() + \", I see your favorite language is \" + favorite_languages[name].title() + \"!\")" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "使用keys()确定某个人是否接受了调查。下面的代码确定Erin是否接受了调查：" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "favorite_languages = {\n", "'jen': 'python',\n", "'sarah': 'c',\n", "'edward': 'ruby',\n", "'phil': 'python',\n", "}\n", "if 'erin' not in favorite_languages.keys():\n", " print(\"Erin, please take our poll!\")" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "方法keys()并非只能用于遍历；实际上，它返回一个列表，其中包含字典中的所有键，因此\n", "处的代码行只是核实'erin'是否包含在这个列表中。由于她并不包含在这个列表中，因此打印\n", "一条消息，邀请她参加调查" ] }, { "cell_type": "markdown", "metadata": {}, "source": [] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**3 按顺序遍历字典中的所有键**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "字典总是明确地记录键和值之间的关联关系，但获取字典的元素时，获取顺序是不可预测的。\n", "这不是问题，因为通常你想要的只是获取与键相关联的正确的值。\n", "要以特定的顺序返回元素，一种办法是在for循环中对返回的键进行排序。为此，可使用函\n", "数sorted()来获得按特定顺序排列的键列表的副本：" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "favorite_languages = {\n", "'jen': 'python',\n", "'sarah': 'c',\n", "'edward': 'ruby',\n", "'phil': 'python',\n", "}\n", "for name in sorted(favorite_languages.keys()):\n", " print(name.title() + \", thank you for taking the poll.\")" ] }, { "cell_type": "markdown", "metadata": { "collapsed": true }, "source": [ "**4 遍历字典中的所有值**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "如果你感兴趣的主要是字典包含的值，可使用方法values()，
它返回一个值列表，而不包含\n", "任何键。" ] }, { "cell_type": "code", "execution_count": 4, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "The following languages have been mentioned:\n", "Python\n", "C\n", "Ruby\n", "Python\n" ] } ], "source": [ "favorite_languages = {\n", "'jen': 'python',\n", "'sarah': 'c',\n", "'edward': 'ruby',\n", "'phil': 'python',}\n", "print(\"The following languages have been mentioned:\")\n", "for language in favorite_languages.values():\n", " print(language.title())" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "这种做法提取字典中所有的值，而没有考虑是否重复。涉及的值很少时，这也许不是问题，
\n", "但如果被调查者很多，最终的列表可能包含大量的重复项。
为剔除重复项，可使用集合（ set）。\n", "集合类似于列表，但每个元素都必须是独一无二的：" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "favorite_languages = {\n", "'jen': 'python',\n", "'sarah': 'c',\n", "'edward': 'ruby',\n", "'phil': 'python',}\n", "print(\"The following languages have been mentioned:\")\n", "for language in set(favorite_languages.values()):\n", " print(language.title())" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# 嵌套" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "有时候， 需要将一系列字典存储在列表中，或将列表作为值存储在字典中，这称为嵌套。
你\n", "可以在列表中嵌套字典、在字典中嵌套列表甚至在字典中嵌套字典。正如下面的示例将演示的，
\n", "嵌套是一项强大的功能。" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**1 字典列表**" ] }, { "cell_type": "code", "execution_count": 35, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "{'color': 'green', 'points': 5}\n", "{'color': 'yellow', 'points': 10}\n", "{'color': 'red', 'points': 15}\n" ] } ], "source": [ "alien_0 = {'color': 'green', 'points': 5}\n", "alien_1 = {'color': 'yellow', 'points': 10}\n", "alien_2 = {'color': 'red', 'points': 15}\n", "aliens = [alien_0, alien_1, alien_2]\n", "for alien in aliens:\n", " print(alien)" ] }, { "cell_type": "code", "execution_count": 5, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "{'color': 'green', 'points': 5, 'speed': 'slow'}\n", "{'color': 'green', 'points': 5, 'speed': 'slow'}\n", "{'color': 'green', 'points': 5, 'speed': 'slow'}\n", "{'color': 'green', 'points': 5, 'speed': 'slow'}\n", "{'color': 'green', 'points': 5, 'speed': 'slow'}\n", "...\n", "Total number of aliens: 30\n" ] } ], "source": [ "# 创建一个用于存储外星人的空列表\n", "aliens = []\n", "# 创建30个绿色的外星人\n", "for alien_number in range(30):\n", " new_alien = {'color': 'green', 'points': 5, 'speed': 'slow'}\n", " aliens.append(new_alien)\n", "# 显示前五个外星人\n", "for alien in aliens[:5]:\n", " print(alien)\n", "print(\"...\")\n", "# 显示创建了多少个外星人\n", "print(\"Total number of aliens: \" + str(len(aliens)))" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "在什么情况下需要处理成群结队的外星人呢？想象一下，可能随着游戏的进行，有些外星人
\n", "会变色且移动速度会加快。必要时，我们可以使用for循环和if语句来修改某些外星人的颜色。
\n", "例如，要将前三个外星人修改为黄色的、速度为中等且值10个点，可以这样做：" ] }, { "cell_type": "code", "execution_count": 6, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "{'color': 'yellow', 'points': 10, 'speed': 'medium'}\n", "{'color': 'yellow', 'points': 10, 'speed': 'medium'}\n", "{'color': 'yellow', 'points': 10, 'speed': 'medium'}\n", "{'color': 'green', 'points': 5, 'speed': 'slow'}\n", "{'color': 'green', 'points': 5, 'speed': 'slow'}\n", "...\n" ] } ], "source": [ "# 创建一个用于存储外星人的空列表\n", "aliens = []\n", "# 创建30个绿色的外星人\n", "for alien_number in range (0,30):\n", " new_alien = {'color': 'green', 'points': 5, 'speed': 'slow'}\n", " aliens.append(new_alien)\n", "\n", "for alien in aliens[0:3]:\n", " if alien['color'] == 'green':\n", " alien['color'] = 'yellow'\n", " alien['speed'] = 'medium'\n", " alien['points'] = 10\n", " \n", "# 显示前五个外星人\n", "for alien in aliens[0:5]:\n", " print(alien)\n", "print(\"...\")" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "你可以进一步扩展这个循环，在其中添加一个elif代码块，将黄色外星人改为移动速度快且
\n", "值15个点的红色外星人，如下所示（这里只列出了循环，而没有列出整个程序）：" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "# 创建一个用于存储外星人的空列表\n", "aliens = []\n", "# 创建30个绿色的外星人\n", "for alien_number in range (0,30):\n", " new_alien = {'color': 'green', 'points': 5, 'speed': 'slow'}\n", " aliens.append(new_alien)\n", " \n", "for alien in aliens[0:3]:\n", " if alien['color'] == 'green':\n", " alien['color'] = 'yellow'\n", " alien['speed'] = 'medium'\n", " alien['points'] = 10\n", " elif alien['color'] == 'yellow':\n", " alien['color'] = 'red'\n", " alien['speed'] = 'fast'\n", " alien['points'] = 15\n", "# 显示前五个外星人\n", "for alien in aliens[0:9]:\n", " print(alien)\n", "print(\"...\")" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**2 在字典中存储列表**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "有时候， 需要将列表存储在字典中，而不是将字典存储在列表中。
例如，你如何描述顾客点的比萨呢？如果使用列表，\n", "
只能存储要添加的比萨配料；但如果使用字典，就不仅可在其中包含\n", "配料列表，还可包含其他有关比萨的描述。" ] }, { "cell_type": "code", "execution_count": 36, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "You ordered a thick-crust pizza with the following toppings:\n", "\tmushrooms\n", "\textra cheese\n" ] } ], "source": [ "# 存储所点比萨的信息\n", "pizza = {\n", "'crust': 'thick',\n", "'toppings': ['mushrooms', 'extra cheese'],\n", "}\n", "\n", "# 概述所点的比萨\n", "print(\"You ordered a \" + pizza['crust'] + \"-crust pizza \" +\n", "\"with the following toppings:\")\n", "\n", "for topping in pizza['toppings']:\n", " print(\"\\t\" + topping)" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "每当需要在字典中将一个键关联到多个值时，都可以在字典中嵌套一个列表。在本章前面有\n", "关喜欢的编程语言的示例中，如果将每个人的回答都存储在一个列表中，被调查者就可选择多种\n", "喜欢的语言。" ] }, { "cell_type": "code", "execution_count": 39, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", "(Jen)'s favorite languages are:\n", "\tPython\n", "\tRuby\n", "\n", "Sarah's favorite languages are:\n", "\tC\n", "\n", "Edward's favorite languages are:\n", "\tRuby\n", "\tGo\n", "\n", "Phil's favorite languages are:\n", "\tPython\n", "\tHaskell\n" ] } ], "source": [ "favorite_languages = {\n", "'jen': ['python', 'ruby'],\n", "'sarah': ['c'],\n", "'edward': ['ruby', 'go'],\n", "'phil': ['python', 'haskell'],\n", "}\n", "\n", "for name, languages in favorite_languages.items():\n", " print(\"\\n\" + name.title() + \"'s favorite languages are:\")\n", " for language in languages:\n", " print(\"\\t\" + language.title())" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**3 在字典中存储字典**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "在下面的程序中，对于每位用户，我们都存储了其三项信\n", "息：名、姓和居住地；为访问这些信息，我们遍历所有的用户名，
并访问与每个用户名相关联的\n", "信息字典：" ] }, { "cell_type": "code", "execution_count": 21, "metadata": {}, "outputs": [], "source": [ "users = {\n", "'aeinstein': {\n", "'first': 'albert',\n", "'last': 'einstein',\n", "'location': 'princeton',\n", "},\n", "'mcurie': {\n", "'first': 'marie',\n", "'last': 'curie',\n", "'location': 'paris',\n", "},\n", "}" ] }, { "cell_type": "code", "execution_count": 9, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "\n", "Username: aeinstein\n", "\tFull name: Albert Einstein\n", "\tLocation: Princeton\n", "\n", "Username: mcurie\n", "\tFull name: Marie Curie\n", "\tLocation: Paris\n" ] } ], "source": [ "for username, user_info in users.items():\n", " print(\"\\nUsername: \" + username)\n", " full_name = user_info['first'] + \" \" + user_info['last']\n", " location = user_info['location']\n", " print(\"\\tFull name: \" + full_name.title())\n", " print(\"\\tLocation: \" + location.title())" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# set\n", "set和dict类似，也是**一组key的集合，但不存储value**。由于key不能重复，**在set中，没有重复的key。**\n", "\n", "要创建一个set，需要提供一个list作为输入集合：\n", "\n" ] }, { "cell_type": "code", "execution_count": 30, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3}" ] }, "execution_count": 30, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s = set([1, 2, 3])\n", "s" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "传入的参数[1, 2, 3]是一个list，而显示的{1, 2, 3}只是告诉你这个set内部有1，2，3这3个元素，显示的顺序也不表示set是有序的" ] }, { "cell_type": "markdown", "metadata": { "collapsed": true }, "source": [ "重复元素在set中自动被过滤：" ] }, { "cell_type": "code", "execution_count": 63, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3}" ] }, "execution_count": 63, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s = set([1, 1, 2, 2, 3, 3])\n", "s" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "通过add(key)方法可以添加元素到set中，可以重复添加，但不会有效果：" ] }, { "cell_type": "code", "execution_count": 64, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3, 4}" ] }, "execution_count": 64, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s.add(4)\n", "s" ] }, { "cell_type": "code", "execution_count": 65, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3, 4}" ] }, "execution_count": 65, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s.add(4)\n", "s" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "通过remove(key)方法可以删除元素：" ] }, { "cell_type": "code", "execution_count": 66, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3}" ] }, "execution_count": 66, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s.remove(4)\n", "s" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "set可以看成数学意义上的无序和无重复元素的集合，因此，两个set可以做数学意义上的交集、并集等操作：" ] }, { "cell_type": "code", "execution_count": 35, "metadata": {}, "outputs": [], "source": [ "s1 = set([1, 2, 3])\n", "s2 = set([2, 3, 4])" ] }, { "cell_type": "code", "execution_count": 36, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{2, 3}" ] }, "execution_count": 36, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s1 & s2" ] }, { "cell_type": "code", "execution_count": 37, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "{1, 2, 3, 4}" ] }, "execution_count": 37, "metadata": {}, "output_type": "execute_result" } ], "source": [ "s1 | s2" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "set和dict的唯一区别仅在于没有存储对应的value，但是，set的原理和dict一样，
\n", "所以，同样不可以放入可变对象，因为无法判断两个可变对象是否相等，​
\n", "也就无法保证set内部“不会有重复元素”。试试把list放入set，看看是否会报错。" ] }, { "cell_type": "markdown", "metadata": {}, "source": [] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# 再议不可变对象\n", "str是不变对象，而list是可变对象。
\n", "对于可变对象，比如list，对list进行操作，list内部的内容是会变化的，比如：" ] }, { "cell_type": "code", "execution_count": 43, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "['a', 'b', 'c']" ] }, "execution_count": 43, "metadata": {}, "output_type": "execute_result" } ], "source": [ "a = ['c', 'b', 'a']\n", "a.sort()\n", "a" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "对于不可变对象，比如str:
\n", "虽然字符串有个replace()方法，也确实变出了'Abc'，但变量a最后仍是'abc'" ] }, { "cell_type": "code", "execution_count": 44, "metadata": {}, "outputs": [ { "ename": "TypeError", "evalue": "'str' object does not support item assignment", "output_type": "error", "traceback": [ "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m", "\u001b[1;31mTypeError\u001b[0m Traceback (most recent call last)", "\u001b[1;32m\u001b[0m in \u001b[0;36m\u001b[1;34m()\u001b[0m\n\u001b[0;32m 1\u001b[0m \u001b[0ma\u001b[0m\u001b[1;33m=\u001b[0m\u001b[1;34m'abc'\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[1;32m----> 2\u001b[1;33m \u001b[0ma\u001b[0m\u001b[1;33m[\u001b[0m\u001b[1;36m0\u001b[0m\u001b[1;33m]\u001b[0m\u001b[1;33m=\u001b[0m\u001b[1;34m'A'\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m\u001b[0;32m 3\u001b[0m \u001b[0ma\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n", "\u001b[1;31mTypeError\u001b[0m: 'str' object does not support item assignment" ] } ], "source": [ "a='abc'\n", "a[0]='A'\n", "a" ] }, { "cell_type": "code", "execution_count": 47, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "abc 2610455307744\n", "Abc 2610495922840\n", "abc 2610455307744\n" ] } ], "source": [ "a = 'abc'\n", "print(a,id(a))\n", "print(a.replace('a', 'A'),id(a.replace('a', 'A')))\n", "print(a,id(a))" ] }, { "cell_type": "code", "execution_count": 40, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "'Abc'" ] }, "execution_count": 40, "metadata": {}, "output_type": "execute_result" } ], "source": [ "a = 'abc'\n", "b = a.replace('a', 'A')\n", "b" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "a是变量，而'abc'才是字符串对象！
\n", "对象a的内容是'abc'，\n", "但其实是指，a本身是一个变量，它指向的对象的内容才是'abc'：" ] }, { "cell_type": "raw", "metadata": {}, "source": [ "┌───┐ ┌───────┐\n", "│ a │─────────────────>│ 'abc' │\n", "└───┘ └───────┘\n", "┌───┐ ┌───────┐\n", "│ b │─────────────────>│ 'Abc' │\n", "└───┘ └───────┘\n", "调用a.replace('a', 'A')时，实际上调用方法replace是作用在字符串对象'abc'上的，而这个方法虽然名字叫replace，但却没有改变字符串'abc'的内容。相反，replace方法创建了一个新字符串'Abc'并返回，如果我们用变量b指向该新字符串，就容易理解了，变量a仍指向原有的字符串'abc'，但变量b却指向新字符串'Abc'了。" ] }, { "cell_type": "raw", "metadata": {}, "source": [ "对于不变对象来说，调用对象自身的任意方法，也不会改变该对象自身的内容。\n", "相反，这些方法会创建新的对象并返回，这样，就保证了不可变对象本身永远是不可变的。" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# 函数 input()的工作原理" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "函数input()让程序暂停运行，等待用户输入一些文本。获取用户输入后， Python将其存储在\n", "一个变量中，以方便你使用" ] }, { "cell_type": "code", "execution_count": 21, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Tell me something, and I will repeat it back to you: clever\n", "clever\n" ] } ], "source": [ "message = input(\"Tell me something, and I will repeat it back to you: \")\n", "print(message)" ] }, { "cell_type": "code", "execution_count": 22, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "If you tell us who you are, we can personalize the messages you see.\n", "What is your first name? a\n", "\n", "Hello, a!\n" ] } ], "source": [ "prompt = \"If you tell us who you are, we can personalize the messages you see.\"\n", "prompt += \"\\nWhat is your first name? \"\n", "name = input(prompt)\n", "print(\"\\nHello, \" + name + \"!\")" ] }, { "cell_type": "code", "execution_count": 24, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "How old are you? 16\n" ] }, { "data": { "text/plain": [ "False" ] }, "execution_count": 24, "metadata": {}, "output_type": "execute_result" } ], "source": [ "age = input(\"How old are you? \")\n", "int(age) >= 18" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] }, { "cell_type": "markdown", "metadata": {}, "source": [ "# 使用 while 循环来处理列表和字典" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**1 在列表之间移动元素**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "假设有一个列表，其中包含新注册但还未验证的网站用户；验证这些用户后，如何将他们移\n", "到另一个已验证用户列表中呢？一种办法是使用一个while循环，在验证用户的同时将其从未验\n", "证用户列表中提取出来，再将其加入到另一个已验证用户列表中。" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "# 首先，创建一个待验证用户列表\n", "# 和一个用于存储已验证用户的空列表\n", "unconfirmed_users = ['alice', 'brian', 'candace']\n", "confirmed_users = []" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "# 验证每个用户，直到没有未验证用户为止\n", "# 将每个经过验证的列表都移到已验证用户列表中\n", "while unconfirmed_users:\n", " current_user = unconfirmed_users.pop()\n", " print(\"Verifying user: \" + current_user.title())\n", " confirmed_users.append(current_user)\n", " \n", "# 显示所有已验证的用户\n", "print(\"\\nThe following users have been confirmed:\")\n", "for confirmed_user in confirmed_users:\n", " print(confirmed_user.title())" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**2 删除包含特定值的所有列表元素**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "我们使用函数remove()来删除列表中的特定值，这之所以可行，是因为要删除\n", "的值在列表中只出现了一次。如果要删除列表中所有包含特定值的元素，该怎么办呢？
\n", "假设你有一个宠物列表，其中包含多个值为'cat'的元素。要删除所有这些元素，可不断运\n", "行一个while循环，直到列表中不再包含值'cat'，如下所示：" ] }, { "cell_type": "code", "execution_count": 25, "metadata": {}, "outputs": [], "source": [ "pets = ['dog', 'cat', 'dog', 'goldfish', 'cat', 'rabbit', 'cat']" ] }, { "cell_type": "code", "execution_count": 27, "metadata": {}, "outputs": [ { "data": { "text/plain": [ "['cat', 'dog', 'goldfish', 'cat', 'rabbit', 'cat']" ] }, "execution_count": 27, "metadata": {}, "output_type": "execute_result" } ], "source": [ "pets.remove('dog')\n", "pets" ] }, { "cell_type": "code", "execution_count": 28, "metadata": {}, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "['cat', 'dog', 'goldfish', 'cat', 'rabbit', 'cat']\n", "['dog', 'goldfish', 'rabbit']\n" ] } ], "source": [ "\n", "print(pets)\n", "while 'cat' in pets:\n", " pets.remove('cat')\n", "print(pets)" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [] } ], "metadata": { "kernelspec": { "display_name": "Python 3", "language": "python", "name": "python3" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 3 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", "version": "3.6.13" }, "toc": { "base_numbering": 1, "nav_menu": {}, "number_sections": true, "sideBar": true, "skip_h1_title": false, "title_cell": "Table of Contents", "title_sidebar": "Contents", "toc_cell": false, "toc_position": {}, "toc_section_display": true, "toc_window_display": true } }, "nbformat": 4, "nbformat_minor": 2 }