第十四节，基本数据类型，列表list

创建列表 

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'seven', 'eric']
#或
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"""

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#list将16进制转换成字符串
a = "林贵秀"
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
print(b)
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'seven', 'eric']
print(a[0])
print(a[1])
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#切片
a = ['alex', 'seven', 'eric']
print(a[0:2])
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'seven', 'eric']
print(len(a))
#输出 3 统计列表里有多少个元素

　　循环列表

　　　　while循环

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#while循环
a = ['alex', 'seven', 'eric']
b = 0
while b < len(a): #len(统计列表里的元素)
    print(a[b])
    b += 1
#循环出列表里的所有元素

　　　　for循环

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#for循环
a = ['alex', 'seven', 'eric']
for b in a: #b为自定义循环变量
    print(b)
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'seven', 'eric']
a.append("linguixiu")
print(a)
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'seven', 'eric', 'seven',]
b = a.count("seven")
print(b)
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'seven', 'eric', 'seven',]
b = ["1", "2", "3"]
a.extend(b)
print(a)
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'eric', 'seven']
print(a.index("seven"))
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'eric', 'seven']
a.insert(0,"guixiu")
print(a)
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'eric', 'seven']
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
print(a)
#打印a ['eric', 'seven'] 移除了0位置的元素

print(b)
#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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'eric', 'seven']
a.remove("eric")
print(a)
#打印出 ['alex', 'seven'] 移除了eric

　　reverse(self)

　　"""(反转元素顺序)"""

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'eric', 'seven']
a.reverse()
print(a)
#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]

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'eric', 'seven']
del a[0]
print(a)
#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]

　　

#!/usr/bin/env python
# -*- coding:utf-8 -*-
a = ['alex', 'eric', 'seven']
del a[0:2]
print(a)
#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)"""

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#list将16进制转换成字符串
a = ['林', '贵', '秀']
a.clear()
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

#!/usr/bin/env python
# -*- coding:utf-8 -*-
#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
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')]
print(a[0])#=四川， 索引列表第0个元素
print(a[1])#{'省会': '成都'}, 索引列表第1个元素
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
print(a[2])#=('自贡', '内江', '乐山')  索引列表里的第二个元素
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
#最终输出
# 四川
# {'省会': '成都'}
# 成都
# ('自贡', '内江', '乐山')
# 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