Python学习笔记之列表和元组

列表是我们最以后最常用的数据类型之一，通过列表可以对数据实现最方便的存储、修改等操作，以[]标识，中间用逗号隔开

names = [‘aa‘,"bb",‘cc‘] #names变量用列表来赋值

列表索引以0开头

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]print(names[0])#aaprint(names[-1])#eeprint(names[:-1])#[‘aa‘, ‘bb‘, ‘cc‘, ‘dd‘]print(names[:])#[‘aa‘, ‘bb‘, ‘cc‘, ‘dd‘, ‘ee‘]print(names[1:3])#[‘bb‘, ‘cc‘]顾头不顾尾print(names[1::2])#[‘bb‘, ‘dd‘]步长为2

append()追加,可以是任意参数，作用是往已有列表中添加元素，如果添加的是列表，就被当成一个元素存在原列表中，只使list长度增加1.

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]#names.append(‘ff‘)print(names)#[‘aa‘, ‘bb‘, ‘cc‘, ‘dd‘, ‘ee‘, ‘ff‘]names.append(["d1","d2"])print(names)#[‘aa‘, ‘bb‘, ‘cc‘, ‘dd‘, ‘ee‘, [‘d1‘, ‘d2‘]]

insert()插入 insert(index,obj)列表与方法之间用点号相隔，括号内需要添入的参数分别是索引和要插入的元素

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]names.insert(2,"a1")print(names)#[‘aa‘, ‘bb‘, ‘a1‘, ‘cc‘, ‘dd‘, ‘ee‘]

修改

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]names[2]="a1"print(names)#[‘aa‘, ‘bb‘, ‘a1‘, ‘dd‘, ‘ee‘]

删除

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]

方式1 del：

del names[2]print(names)#[‘aa‘, ‘bb‘, ‘dd‘, ‘ee‘]

方式2 remove：names.remove("cc")print(names)#[‘aa‘, ‘bb‘, ‘dd‘, ‘ee‘]

方式3 pop：names.pop()print(names)#[‘aa‘, ‘bb‘, ‘cc‘, ‘dd‘]默认是删除最后一个，指定索引就删除对于索引的元素

这里按索引names.pop(2)print(names)#[‘aa‘, ‘bb‘, ‘dd‘, ‘ee‘]

扩展extend

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]aa = [1,2,3]names.extend(aa)print(names,aa)#[‘aa‘, ‘bb‘, ‘cc‘, ‘dd‘, ‘ee‘, 1, 2, 3] [1, 2, 3]

复制copy

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]names2 = names.copy()print(names2)#[‘aa‘, ‘bb‘, ‘cc‘, ‘dd‘, ‘ee‘]

计数count

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘aa‘]names2 = names.count("aa")print(names2)#2

清空clear

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘aa‘]names.clear()print(names)#[]

排序sort、reverse

names = [‘1aa‘,"Cbb",‘1cc‘,‘dd‘,‘aa‘]names.sort()print(names)#[‘1aa‘, ‘1cc‘, ‘Cbb‘, ‘aa‘, ‘dd‘]按照ASCII码表的顺序来排序names2 = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]names2.reverse()print(names2)#[‘ee‘, ‘dd‘, ‘cc‘, ‘bb‘, ‘aa‘]

下标index

names = [‘aa‘,"bb",‘cc‘,‘dd‘,‘ee‘]print(names.index(‘bb‘))#1

元组

元组其实跟列表差不多，也是存一组数，只不是它一旦创建，便不能再修改，所以又叫只读列表

names = (‘aa‘,"bb",‘aa‘,‘dd‘,‘ee‘)print(names.count("aa"))#2print(names.index(‘bb‘))#1