第4章 Python-字典與集合

第4章

字典與集合Chap4DictionaryandSetADictionary字典BSet集合2字典4.13為什么要使用字典？salaries['Lilin']4>>>names=['Mayue','Lilin','Wuyun']>>>salaries=[3000,4500,8000]>>>print(salaries[names.index('Lilin')])4500Source某公司人事部門讓技術(shù)部門用Python構(gòu)建一個簡易的員工信息表，包含員工的姓名和工資信息。根據(jù)信息表查詢員工Linlin的工資。字典什么是字典?——一種映射類型鍵（key）值（value）key-value對5鍵是唯一的：數(shù)字字符串元組不可變對象字典aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}6字典中的元素是無序的keyvalue'Mayue'3000'Lilin'4500'Wuyun'8000>>>sorted(aInfo)['Lilin','Mayue','Wuyun']Source4.1.1創(chuàng)建字典7創(chuàng)建字典8>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}Source直接創(chuàng)建創(chuàng)建字典9>>>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()函數(shù)創(chuàng)建創(chuàng)建字典10>>>gInfo={}.fromkeys(('Mayue','Lilin','Wuyun'),3000)>>>print(gInfo){'Lilin':3000,'Mayue':3000,'Wuyun':3000}Source用方法fromkeys(seq[,value])創(chuàng)建創(chuàng)建員工信息表時將所有員工的工資默認值設(shè)置為3000生成字典>>>names=['Mayue','Lilin','Wuyun']>>>salaries=[3000,4500,8000]>>>dict(zip(names,salaries)){'Mayue':3000,'Lilin':4500,'Wuyun':8000}Source11已知有姓名列表和工資列表，如何生成字典類型的員工信息表？生成字典12對于幾個公司的財經(jīng)數(shù)據(jù)，如何構(gòu)造公司代碼和股票價格的字典？

pList=[('AXP','AmericanExpressCompany','78.51'),('BA','TheBoeingCompany','184.76'),

('CAT','CaterpillarInc.','96.39'),

('CSCO','CiscoSystems,Inc.','33.71'),

('CVX','ChevronCorporation','106.09')]生成字典13對于幾個公司的財經(jīng)數(shù)據(jù)，如何構(gòu)造公司代碼和股票價格的字典？aDict={'AXP':'78.51','BA':'184.76','CAT':'96.39','CSCO':'33.71','CVX':'106.09'}算法分析：可用循環(huán)將公司代碼和股票價格分別append到一個新列表中，再利用zip()和dict()函數(shù)將這兩個列表轉(zhuǎn)化成字典。4.1.2字典的基本操作14字典的基本操作15鍵值查找字典更新添加元素成員判斷刪除元素1.鍵值查找>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>aInfo['Lilin']4500Source162.字典更新>>>aInfo['Lilin']=9999>>>aInfo{'Wuyun':8000,'Mayue':3000,'Lilin':9999}Source173.添加元素>>>aInfo={'Mayue':3000,'Lilin':9999,'Wuyun':8000}>>>aInfo['Liuxi']=6000>>>aInfo{'Wuyun':8000,'Liuxi':6000,'Mayue':3000,'Lilin':9999}Source183.添加元素>>>d={}>>>d["Liuyue"]=[65,88,90]>>>d{'Liuyue':[65,88,90]}>>>d['Majin']=[89]>>>d['Majin']+=[94]>>>d["Majin"]

+=[85]>>>d{'Liuyue':[65,88,90],'Majin':[89,94,85]}Source194.成員判斷>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>'Liuyun'

inaInfoFalseSource205.刪除元素>>>delaInfo>>>aInfoTraceback(mostrecentcalllast):File"<pyshell#30>",line1,in<module>aInfoNameError:name'aInfo'isnotdefined>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>delaInfo['Lilin']>>>aInfo{'Mayue':3000,'Wuyun':8000}Source21字典的內(nèi)建函數(shù)22dict()len()hash()>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>len(aInfo)3>>>hash('Mayue')7716305958664889313>>>testList=[1,2,3]>>>hash(testList)Traceback(mostrecentcalllast):File"<pyshell#1>",line1,in<module>hash(testList)TypeError:unhashabletype:'list'Source字典方法23clear()copy()fromkeys()get()items()keys()pop()setdefault()update()values()字典方法>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>aInfo.keys()dict_keys(['Mayue','Lilin','Wuyun'])>>>aInfo.values()dict_values([3000,4500,8000])>>>aInfo.items()dict_items([('Mayue',3000),('Lilin',4500),('Wuyun',8000)])Source24keys()values()items()字典方法>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>print(aInfo.get('Qiqi'))None>>>print(aInfo.get('Lilin'))4500>>>aInfo['Qiqi']Traceback(mostrecentcalllast):File"<pyshell#2>",line1,in<module>aInfo['Qiqi']KeyError:'Qiqi'Source25get()字典方法>>>stock={'AXP':78.51,'BA':184.76}>>>stock['AAA']Traceback(mostrecentcalllast):File"<stdin>",line1,in<module>KeyError:'AAA'Source下面兩個程序都通過鍵查找值，區(qū)別在哪里？你更喜歡哪一個？？>>>stock={'AXP':78.51,'BA':184.76}>>>print(stock.get('AAA'))NoneSource26字典方法>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>aInfoBackup=aInfo.copy()>>>aInfoBackup{'Mayue':3000,'Lilin':4500,'Wuyun':8000}Source27copy()字典方法>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>aInfo.pop('Lilin')4500>>>aInfo{'Mayue':3000,'Wuyun':8000}Source28pop()字典方法>>>aInfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>aInfo.clear()>>>aInfo{}Source29clear()字典方法>>>anfo={'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>bInfo={}>>>bInfo.update(aInfo)>>>bInfo{'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>cInfo={'Mayue':4000,'Wanqi':6000,'Lilin':9999}>>>aInfo{'Mayue':3000,'Lilin':4500,'Wuyun':8000}>>>aInfo.update(cInfo)>>>aInfo{'Mayue':4000,'Lilin':9999,'Wanqi':6000,'Wuyun':8000}Source30update()字典方法>>>aInfo.setdefault('Lilin',None)#與aInfo.get('Lilin')和aInfo.setdefault('Lilin')效果一樣9999>>>aInfo.setdefault('Jinhe',None)#與aInfo.setdefault('Jinhe')效果一樣>>>aInfo.setdefault('Qiqi',8000)8000>>>aInfo{'Mayue':4000,'Lilin':9999,'Wanqi':6000,'Wuyun':8000,'Jinhe':None,'Qiqi':8000}Source31setdefault()字典方法簡單應(yīng)用已知有員工姓名和工資信息表{'Wangdachui':3000,'Niuyun':2000,'Linling':4500,'Tianqi':8000}，如何單獨輸出員工姓名和工資金額？？32>>>aInfo={'Wangdachui':3000,'Niuyun':2000,'Linling':4500,'Tianqi':8000}>>>aInfo.keys()dict_keys(['Tianqi','Wangdachui','Niuyun','Linling'])>>>aInfo.values()dict_values([8000,3000,2000,4500])Source字典方法簡單應(yīng)用>>>aInfo={'Wangdachui':3000,'Niuyun':2000,'Linling':4500}>>>bInfo={'Wangdachui':4000,'Niuyun':9999,'Wangzi':6000}>>>aInfo.update(bInfo)>>>aInfo{'Wangzi':6000,'Linling':4500,'Wangdachui':4000,'Niuyun':9999}Source人事部門有兩份人員和工資信息表，第一份是原有信息，第二份是公司中有工資更改人員和新進人員的信息，如何處理可以較快地獲得完整的信息表？？33集合4.2集合>>>names=['Wangdachui','Niuyun','Wangzi','Wangdachui','Linling','Niuyun']>>>namesSet=set(names)>>>namesSet{'Wangzi','Wangdachui','Niuyun','Linling'}Source人事部門的一份工資信息表登記時由于工作人員的疏忽有部分姓名重復(fù)登記了，如何快速解決這個問題？？35集合什么是集合?

一個無序不重復(fù)的元素的組合可變集合（set）不可變集合（frozenset）36去重集合37>>>aSet={1,2,3}>>>names=['Mayue','Lilin','Wanqi','Mayue','Lilin']>>>names['Mayue','Lilin','Wanqi','Mayue','Lilin']>>>nameset=set(names)>>>nameset{'Mayue','Wanqi','Lilin'}>>>type(nameset)<class'set'>Source集合的創(chuàng)建>>>aSet=set('hello')>>>aSet{'h','e','l','o'}>>>fSet=frozenset('hello')>>>fSetfrozenset({'h','e','l','o'})>>>type(aSet)<class'set'>>>>type(fSet)<class'frozenset'>Source38大括號集合的基本操作>>>aSet=set('sunrise')>>>bSet=set('sunset')>>>'u'

inaSetTrue>>>aSet==bSetFalse>>>aSet<bSetFalse>>>set('sun')<aSetTrueSource數(shù)學(xué)符號Python符號innotin===≠!=?<?<=?>?>=標(biāo)準類型運算符39集合的基本操作>>>aSet=set('sunrise')>>>bSet=set('sunset')>>>aSet&bSet{'u','s','e','n'}>>>aSet|bSet{'e','i','n','s','r','u','t'}>>>aSet-bSet{'i','r'}Source數(shù)學(xué)符號Python符號∩&∪|-或\-Δ^集合類型運算符運算符可復(fù)合&=|=-=^=40>>>aSet=set('sunrise')>>>bSet=set('sunset')>>>aSet^bSet{'i','r','t'}>>>aSet-=set('sun')>>>aSet{'e','i','r'}Source集合內(nèi)建函數(shù)41>>>aSet={1,2,3}>>>type(aSet)<class'set'>>>>len(aSet)3Sourcelen()集合內(nèi)建函數(shù)>>>aSet=set('sunrise')>>>bSet=set('sunset')Sourceissubset(t)issuperset(t)union(t)intersection(t)difference(t)symmetric_difference(t)copy()42面向所有集合>>>aSet.issu