第十四节，基本数据类型，列表list
创建列表
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'seven', 'eric'] 4 #或 5 a = list(['alex', 'seven', 'eric'])
list转换列表
"""(转换成列表，需要转换的可迭代数据变量) 注意：能转换成列表的必须是可迭代的，也就是可以被for循环的"""
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 #list将16进制转换成字符串 4 a = "林贵秀" 5 b = list(a)#将一个字符串转换成一个列表，只要是可以被for循环的都可以用list转换成列表 6 print(b) 7 #输出 ['林', '贵', '秀']
字符串，元组，列表 > 都可以转换成列表，转换成列表都是可以被for循环的，for循环每次循环到的数据就是列表的一个元素
基本操作：
索引
切片
追加
删除
长度
循环
包含
打印列表里的元素
打印出列表里的元素是以列表变量加元素下标的方式来打印
索引
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'seven', 'eric'] 4 print(a[0]) 5 print(a[1]) 6 #输出 alex seven 这样就打印出了，第零个和第一个下标的元素
切片
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 #切片 4 a = ['alex', 'seven', 'eric'] 5 print(a[0:2]) 6 #输出 alex seven 这样就切片出了，第零一个和第二个下标的元素
统计列表里有多少个元素
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'seven', 'eric'] 4 print(len(a)) 5 #输出 3 统计列表里有多少个元素
循环列表
while循环
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 #while循环 4 a = ['alex', 'seven', 'eric'] 5 b = 0 6 while b < len(a): #len(统计列表里的元素) 7 print(a[b]) 8 b += 1 9 #循环出列表里的所有元素
for循环
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 #for循环 4 a = ['alex', 'seven', 'eric'] 5 for b in a: #b为自定义循环变量 6 print(b) 7 #循环出列表里的所有元素
append(self, p_object)
"""(追加列表)"""要追加的元素
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'seven', 'eric'] 4 a.append("linguixiu") 5 print(a) 6 #打印出 ['alex', 'seven', 'eric', 'linguixiu'] 也就是追加了一个元素
count(self, value)
"""(统计元素在列表里出现的次数)"""要统计的元素
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'seven', 'eric', 'seven',] 4 b = a.count("seven") 5 print(b) 6 #打印出 2 统计到seven在列表中出现两次
extend(self, iterable)
"""(扩展列表)"""要扩展的可迭代变量：可迭代是只要是能通过for循环出来的都为可迭代
也就是可以将一个列表扩展到另一个列表
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'seven', 'eric', 'seven',] 4 b = ["1", "2", "3"] 5 a.extend(b) 6 print(a) 7 #打印出 ['alex', 'seven', 'eric', 'seven', '1', '2', '3'] 将一个列表扩展到另一个列表
index(self, value, start=None, stop=None)
"""(获取一个元素在列表里的索引下标)"""要获取的元素
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'eric', 'seven'] 4 print(a.index("seven")) 5 #打印出 2 获取到seven的索引下标为2，默认从0开始所以是2
insert(self, index, p_object)
"""(插入元素)"""要插入的位置，要插入的元素
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'eric', 'seven'] 4 a.insert(0,"guixiu") 5 print(a) 6 #打印出 ['guixiu', 'alex', 'eric', 'seven'] 在0的位置插入guixiu
pop(self, index=None)
"""(移除元素)"""要移除的位置：默认移除后面一个元素
移除的元素还可以重新赋值给一个变量
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'eric', 'seven'] 4 b = a.pop(0)#移除a变量的0位置元素，将移除的元素赋值给b 5 print(a) 6 #打印a ['eric', 'seven'] 移除了0位置的元素 7 8 print(b) 9 #打印b alex 被移除的元素
remove(self, value)
"""(移除某个元素)"""要移除的元素
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'eric', 'seven'] 4 a.remove("eric") 5 print(a) 6 #打印出 ['alex', 'seven'] 移除了eric
reverse(self)
"""(反转元素顺序)"""
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'eric', 'seven'] 4 a.reverse() 5 print(a) 6 #打印出 ['seven', 'eric', 'alex'] 反转元素顺序
删除元素
索引方式删除（删除单个元素）
格式：del 列表变量[要删除的下标]
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'eric', 'seven'] 4 del a[0] 5 print(a) 6 #打印出 ['eric', 'seven'] 删除了0位置的元素
切片方式删除（删除多个元素）
格式：del 列表变量[开始位置：结束位置]
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 a = ['alex', 'eric', 'seven'] 4 del a[0:2] 5 print(a) 6 #打印出 ['seven'] 删除了0和2位置的元素
clear(self)
"""(移除列表所有元素)"""
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 #list将16进制转换成字符串 4 a = ['林', '贵', '秀'] 5 a.clear() 6 print(a)
enumerate(iterable，start=0 )
"""(自定义列表的下标开始位置)列表变量，要定义的开下标数：默认是0开始的"""
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 a = ["电脑", "鼠标", "键盘", "显示器"]
4 for k,v in enumerate(a,1):#因为是有键和值，所以循环要定义两个变量k和v
5 print(k,v)
6 #打印出
7 # 1 电脑
8 # 2 鼠标
9 # 3 键盘
10 # 4 显示器
enumerate（）结合应用，输入商品序号，打印出对应的商品
1 #!/usr/bin/env python
2 # -*- coding:utf-8 -*-
3 #输入商品序号，打印出对应的商品
4 a = ["电脑", "鼠标", "键盘", "显示器"]
5 for k,v in enumerate(a,1):#默认下标号从0开始的enumerate（a,1）设置了从1开始
6 print(k,v)
7 #上面打印出商品的序号和名称
8 b = input("请输入商品序号")#等待用户输入商品序号
9 c = int(b)#将用户输入的序号转换成数字类型
10 d = a[c-1]#将用户输入序号转换成列表索引的下标，默认从0开始的所以要减一
11 print(d)#通过用户输入的索引下标打印出商品
12
13 # 1 电脑
14 # 2 鼠标
15 # 3 键盘
16 # 4 显示器
17 # 请输入商品序号4
18 # 显示器
列表的嵌套，列表里有字典，元组，
用索引的方法输出需要的省份，省会，以及一个市
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 #列表的嵌套，列表里有字典，元组， 4 #用索引的方法输出需要的省份，省会，以及一个市 5 a = ['四川', {'省会': '成都'}, ('自贡', '内江', '乐山'), '云南', {'省会': '昆明'}, ('曲靖', '玉溪', '昭通')] 6 print(a[0])#=四川， 索引列表第0个元素 7 print(a[1])#{'省会': '成都'}, 索引列表第1个元素 8 print(a[1]["省会"])#=成都， 索引列表第1个元素，里的字典的"省会"这个键 9 print(a[2])#=('自贡', '内江', '乐山') 索引列表里的第二个元素 10 print(a[2][0])#=自贡 索引列表里第2个元素，里的元组的第0个元素 11 #最终输出 12 # 四川 13 # {'省会': '成都'} 14 # 成都 15 # ('自贡', '内江', '乐山') 16 # 自贡
class list(object): """ list() -> new empty list list(iterable) -> new list initialized from iterable's items """ def append(self, p_object): # real signature unknown; restored from __doc__ """ L.append(object) -- append object to end """ pass def count(self, value): # real signature unknown; restored from __doc__ """ L.count(value) -> integer -- return number of occurrences of value """ return 0 def extend(self, iterable): # real signature unknown; restored from __doc__ """ L.extend(iterable) -- extend list by appending elements from the iterable """ pass def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__ """ L.index(value, [start, [stop]]) -> integer -- return first index of value. Raises ValueError if the value is not present. """ return 0 def insert(self, index, p_object): # real signature unknown; restored from __doc__ """ L.insert(index, object) -- insert object before index """ pass def pop(self, index=None): # real signature unknown; restored from __doc__ """ L.pop([index]) -> item -- remove and return item at index (default last). Raises IndexError if list is empty or index is out of range. """ pass def remove(self, value): # real signature unknown; restored from __doc__ """ L.remove(value) -- remove first occurrence of value. Raises ValueError if the value is not present. """ pass def reverse(self): # real signature unknown; restored from __doc__ """ L.reverse() -- reverse *IN PLACE* """ pass def sort(self, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__ """ L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*; cmp(x, y) -> -1, 0, 1 """ pass def __add__(self, y): # real signature unknown; restored from __doc__ """ x.__add__(y) <==> x+y """ pass def __contains__(self, y): # real signature unknown; restored from __doc__ """ x.__contains__(y) <==> y in x """ pass def __delitem__(self, y): # real signature unknown; restored from __doc__ """ x.__delitem__(y) <==> del x[y] """ pass def __delslice__(self, i, j): # real signature unknown; restored from __doc__ """ x.__delslice__(i, j) <==> del x[i:j] Use of negative indices is not supported. """ pass def __eq__(self, y): # real signature unknown; restored from __doc__ """ x.__eq__(y) <==> x==y """ pass def __getattribute__(self, name): # real signature unknown; restored from __doc__ """ x.__getattribute__('name') <==> x.name """ pass def __getitem__(self, y): # real signature unknown; restored from __doc__ """ x.__getitem__(y) <==> x[y] """ pass def __getslice__(self, i, j): # real signature unknown; restored from __doc__ """ x.__getslice__(i, j) <==> x[i:j] Use of negative indices is not supported. """ pass def __ge__(self, y): # real signature unknown; restored from __doc__ """ x.__ge__(y) <==> x>=y """ pass def __gt__(self, y): # real signature unknown; restored from __doc__ """ x.__gt__(y) <==> x>y """ pass def __iadd__(self, y): # real signature unknown; restored from __doc__ """ x.__iadd__(y) <==> x+=y """ pass def __imul__(self, y): # real signature unknown; restored from __doc__ """ x.__imul__(y) <==> x*=y """ pass def __init__(self, seq=()): # known special case of list.__init__ """ list() -> new empty list list(iterable) -> new list initialized from iterable's items # (copied from class doc) """ pass def __iter__(self): # real signature unknown; restored from __doc__ """ x.__iter__() <==> iter(x) """ pass def __len__(self): # real signature unknown; restored from __doc__ """ x.__len__() <==> len(x) """ pass def __le__(self, y): # real signature unknown; restored from __doc__ """ x.__le__(y) <==> x<=y """ pass def __lt__(self, y): # real signature unknown; restored from __doc__ """ x.__lt__(y) <==> x<y """ pass def __mul__(self, n): # real signature unknown; restored from __doc__ """ x.__mul__(n) <==> x*n """ pass @staticmethod # known case of __new__ def __new__(S, *more): # real signature unknown; restored from __doc__ """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __ne__(self, y): # real signature unknown; restored from __doc__ """ x.__ne__(y) <==> x!=y """ pass def __repr__(self): # real signature unknown; restored from __doc__ """ x.__repr__() <==> repr(x) """ pass def __reversed__(self): # real signature unknown; restored from __doc__ """ L.__reversed__() -- return a reverse iterator over the list """ pass def __rmul__(self, n): # real signature unknown; restored from __doc__ """ x.__rmul__(n) <==> n*x """ pass def __setitem__(self, i, y): # real signature unknown; restored from __doc__ """ x.__setitem__(i, y) <==> x[i]=y """ pass def __setslice__(self, i, j, y): # real signature unknown; restored from __doc__ """ x.__setslice__(i, j, y) <==> x[i:j]=y Use of negative indices is not supported. """ pass def __sizeof__(self): # real signature unknown; restored from __doc__ """ L.__sizeof__() -- size of L in memory, in bytes """ pass __hash__ = None
列表的功能
转换列表
索引
切片
for循环
长度
删除元素
反转
排序
追加
插入
移除元素
索引位置
统计元素个数
扩展
清除
