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课件网) 第4章 字典与集合 Chap4 Dictionary and Set 字典与集合 ADictionary字典BSet集合字典4.1字典与集合为什么要使用字典？salaries['Lilin']>>>names = ['Mayue','Lilin','Wuyun']>>>salaries= [3000, 4500, 8000]>>>print(salaries[names.index('Lilin')])4500Source某公司人事部门让技术部门用Python构建一个简易的员工信息表，包含员工的姓名和工资信息。根据信息表查询员工Linlin的工资。字典什么是字典 ———一种映射类型键（key）值（value）key-value对键是唯一的：数字字符串元组字典aInfo= {'Mayue': 3000,'Lilin': 4500,'Wuyun': 8000}字典中的元素是无序的keyvalue'Mayue'3000'Lilin'4500'Wuyun'8000>>>sorted(aInfo)['Lilin', 'Mayue', 'Wuyun']Source4.1.1创建字典字典与集合创建字典>>>aInfo= {'Mayue': 3000,'Lilin': 4500,'Wuyun': 8000}Source直接创建创建字典>>>info = [('Mayue', 3000), ('Lilin', 4500), ('Wuyun', 8000)]>>>bInfo=dict(info)>>> print(bInfo){'Lilin': 4500, 'Wuyun': 8000, 'Mayue': 3000}>>>cInfo=dict([['Mayue', 3000], ['Lilin', 4500], ['Wuyun', 8000]])>>>dInfo=dict(Mayue= 3000,Lilin= 4500,Wuyun= 8000)>>>eInfo=dict((('Mayue', 3000), ('Lilin', 4500), ('Wuyun', 8000)))Source用dict()函数创建创建字典>>>gInfo= {}.fromkeys(('Mayue','Lilin','Wuyun'), 3000)>>>print(gInfo){'Lilin': 3000, 'Mayue': 3000, 'Wuyun': 3000}Source用方法fromkeys(seq[, value])创建创建员工信息表时将所有员工的工资默认值设置为3000生成字典>>>names =['Mayue','Lilin','Wuyun']>>> salaries = [3000, 4500, 8000]>>>dict(zip(names,salaries)){'Mayue': 3000, 'Lilin': 4500, 'Wuyun': 8000}Source已知有姓名列表和工资列表，如何生成字典类型的员工信息表？生成字典对于几个公司的财经数据，如何构造公司代码和股票价格的字典？pList= [('AXP', 'American Express Company','78.51'),('BA', 'The Boeing Company','184.76'),('CAT', 'Caterpillar Inc.','96.39'),('CSCO', 'CiscoSystems,Inc.', '33.71'),('CVX', 'Chevron Corporation','106.09')]生成字典对于几个公司的财经数据，如何构造公司代码和股票价格的字典？aDict= {'AXP': '78.51', 'BA': '184.76', 'CAT ': '96.39', 'CSCO': '33.71', 'CVX': '106.09'}算法分析：可用循环将公司代码和股票价格分别append到一个新列表中，再利用zip()和dict()函数将这两个列表转化成字典。4.1.2字典的基本操作字典与集合字典的基本操作键值查找字典更新添加元素成员判断删除元素1.键值查找>>>aInfo= {'Mayue': 3000,'Lilin': 4500,'Wuyun': 8000}>>>aInfo['Lilin']4500Source2.字典更新>>>aInfo['Lilin'] = 9999>>>aInfo{'Wuyun': 8000, 'Mayue': 3000, 'Lilin': 9999}Source3.添加元素>>>aInfo= {'Mayue': 3000,'Lilin': 4500,'Wuyun': 8000}>>>aInfo['Liuxi'] = 6000>>>aInfo{'Wuyun': 8000, 'Liuxi': 6000, 'Mayue': 3000, 'Lilin': 9999}Source4.成员判断>>>aInfo= {'Mayue': 3000,'Lilin': 4500,'Wuyun': 8000}>>>'Liuyun'inaInfoFalseSource5.删除元素>>>aInfo= {'Mayue': 3000,'Lilin': 4500,'Wuyun': 8000}>>>delaInfo['Lilin']>>>aInfo{'Mayue': 3000, 'Wuyun': 8000}Source字典的内建函数字典的内建函数dict()len()hash()>>>aInfo = {'Mayue': 3000,'Lilin': 4500,'Wuyun': 8000}>>>len(aInfo)3>>>hash('Mayue')7716305958664889313>>>testList= [1, 2, 3]>>>hash(testList)Traceback(most recent call last):File "<pyshell#1>", line 1, in <module>hash(te ... ...
