1.列表的表达
[1,2,3,4] ['olive',123] ["python",]
创建列表：
s=[1,2,3] res=list（[1,"python"]）
列表生成式：
用来生成一些有规律的列表；
格式： list_name=['生成规则‘ for i range(num) if ’i的条件‘]
list_name=['生成规则‘ for i ‘可迭代对象’ if ’i的条件‘]
1 a=['a' for i in range(5) if i%2] 2 b=[i+1 for i in range(5)] 3 print(a) 4 print(b) 5 6 #运行结果 7 ['a', 'a'] 8 [1, 2, 3, 4, 5]
D={'a':'1','b':'2','c':'3'}
list_one=[k+'='+v for k,v in D.items()]
L = ['Hello', 'World', 'IBM', 'Apple']
list_two=[s.lower() for s in L]
print(list_one,'
',list_two)
#运行结果
['a=1', 'b=2', 'c=3']
['hello', 'world', 'ibm', 'apple']
2.列表功能
1 class list(object): 2 """ 3 list() -> new empty list 4 list(iterable) -> new list initialized from iterable's items 5 """ 6 def append(self, p_object): # real signature unknown; restored from __doc__ 7 """ L.append(object) -> None -- append object to end """ 8 pass 9 10 def clear(self): # real signature unknown; restored from __doc__ 11 """ L.clear() -> None -- remove all items from L """ 12 pass 13 14 def copy(self): # real signature unknown; restored from __doc__ 15 """ L.copy() -> list -- a shallow copy of L """ 16 return [] 17 18 def count(self, value): # real signature unknown; restored from __doc__ 19 """ L.count(value) -> integer -- return number of occurrences of value """ 20 return 0 21 22 def extend(self, iterable): # real signature unknown; restored from __doc__ 23 """ L.extend(iterable) -> None -- extend list by appending elements from the iterable """ 24 pass 25 26 def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__ 27 """ 28 L.index(value, [start, [stop]]) -> integer -- return first index of value. 29 Raises ValueError if the value is not present. 30 """ 31 return 0 32 33 def insert(self, index, p_object): # real signature unknown; restored from __doc__ 34 """ L.insert(index, object) -- insert object before index """ 35 pass 36 37 def pop(self, index=None): # real signature unknown; restored from __doc__ 38 """ 39 L.pop([index]) -> item -- remove and return item at index (default last). 40 Raises IndexError if list is empty or index is out of range. 41 """ 42 pass 43 44 def remove(self, value): # real signature unknown; restored from __doc__ 45 """ 46 L.remove(value) -> None -- remove first occurrence of value. 47 Raises ValueError if the value is not present. 48 """ 49 pass 50 51 def reverse(self): # real signature unknown; restored from __doc__ 52 """ L.reverse() -- reverse *IN PLACE* """ 53 pass 54 55 def sort(self, key=None, reverse=False): # real signature unknown; restored from __doc__ 56 """ L.sort(key=None, reverse=False) -> None -- stable sort *IN PLACE* """ 57 pass 58 59 def __add__(self, *args, **kwargs): # real signature unknown 60 """ Return self+value. """ 61 pass 62 63 def __contains__(self, *args, **kwargs): # real signature unknown 64 """ Return key in self. """ 65 pass 66 67 def __delitem__(self, *args, **kwargs): # real signature unknown 68 """ Delete self[key]. """ 69 pass 70 71 def __eq__(self, *args, **kwargs): # real signature unknown 72 """ Return self==value. """ 73 pass 74 75 def __getattribute__(self, *args, **kwargs): # real signature unknown 76 """ Return getattr(self, name). """ 77 pass 78 79 def __getitem__(self, y): # real signature unknown; restored from __doc__ 80 """ x.__getitem__(y) <==> x[y] """ 81 pass 82 83 def __ge__(self, *args, **kwargs): # real signature unknown 84 """ Return self>=value. """ 85 pass 86 87 def __gt__(self, *args, **kwargs): # real signature unknown 88 """ Return self>value. """ 89 pass 90 91 def __iadd__(self, *args, **kwargs): # real signature unknown 92 """ Implement self+=value. """ 93 pass 94 95 def __imul__(self, *args, **kwargs): # real signature unknown 96 """ Implement self*=value. """ 97 pass 98 99 def __init__(self, seq=()): # known special case of list.__init__ 100 """ 101 list() -> new empty list 102 list(iterable) -> new list initialized from iterable's items 103 # (copied from class doc) 104 """ 105 pass 106 107 def __iter__(self, *args, **kwargs): # real signature unknown 108 """ Implement iter(self). """ 109 pass 110 111 def __len__(self, *args, **kwargs): # real signature unknown 112 """ Return len(self). """ 113 pass 114 115 def __le__(self, *args, **kwargs): # real signature unknown 116 """ Return self<=value. """ 117 pass 118 119 def __lt__(self, *args, **kwargs): # real signature unknown 120 """ Return self<value. """ 121 pass 122 123 def __mul__(self, *args, **kwargs): # real signature unknown 124 """ Return self*value.n """ 125 pass 126 127 @staticmethod # known case of __new__ 128 def __new__(*args, **kwargs): # real signature unknown 129 """ Create and return a new object. See help(type) for accurate signature. """ 130 pass 131 132 def __ne__(self, *args, **kwargs): # real signature unknown 133 """ Return self!=value. """ 134 pass 135 136 def __repr__(self, *args, **kwargs): # real signature unknown 137 """ Return repr(self). """ 138 pass 139 140 def __reversed__(self): # real signature unknown; restored from __doc__ 141 """ L.__reversed__() -- return a reverse iterator over the list """ 142 pass 143 144 def __rmul__(self, *args, **kwargs): # real signature unknown 145 """ Return self*value. """ 146 pass 147 148 def __setitem__(self, *args, **kwargs): # real signature unknown 149 """ Set self[key] to value. """ 150 pass 151 152 def __sizeof__(self): # real signature unknown; restored from __doc__ 153 """ L.__sizeof__() -- size of L in memory, in bytes """ 154 pass 155 156 __hash__ = None
查看列表的功能属性：
1 a=[1,2] 2 dir(a) 3 4 #解释器运行结果 5 ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ 6 ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__iter__', '__le__' 7 , '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmu 8 l__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'ex 9 tend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']
3.部分功能介绍
1)append(self, p_object):
在原有列表最后位置上追加新元素到列表，不生成新的列表。
1 a=[1,] 2 b=a.append('dog') 3 print(a,type(a)) 4 print(b,type(b)) 5 6 #运行结果 7 [1, 'dog'] <class 'list'> 8 None <class 'NoneType'> #没有返回新列表
2）clear(self):
清空列表里面的元素，不生成新列表。
1 a=[1,2,3,4] 2 b=a.clear() 3 print(a) 4 print(b) 5 6 #运行结果 7 [] 8 None
3）copy(self):
复制一份列表，相当于一次浅拷贝。
1 a=[1,(9,2),3] 2 b=a.copy() 3 print(a,id(a),id(a[1])) 4 print(b,id(b),id(b[1])) 5 6 #赋值 7 c=[1,2,3,4] 8 d=c 9 print(c,id(c)) 10 print(d,id(d)) 11 12 #浅拷贝 13 e=[1,2,(2,3)] 14 f=copy.copy(e) 15 print(e,id(e),id(e[1])) 16 print(f,id(f),id(f[1])) 17 18 #运行结果 19 [1, (9, 2), 3] 5336240 4666792 20 [1, (9, 2), 3] 5335400 4666792 21 [1, 2, 3, 4] 5335640 22 [1, 2, 3, 4] 5335640 23 [1, 2, (2, 3)] 5336280 1678203168 24 [1, 2, (2, 3)] 4668472 1678203168
4）count(self, value):
统计列表中value元素的数量，返回一个int值。
1 a=[1,1,1,2,2,3] 2 b=a.count(1) 3 print(a) 4 print(b,type(b))
5）extend(self, iterable):
把iterable中的每个元素扩展成列表的元素，iterable可以是字符串、列表、字典、元组。
1 a=[1,2,3] 2 b=a.extend("abc") 3 c=a.extend([11,22]) 4 d=a.extend({"dog":22}) 5 print(a) 6 print(b) 7 print(c) 8 print(d) 9 10 #运行结果 11 [1, 2, 3, 'a', 'b', 'c', 11, 22, 'dog'] 12 None 13 None 14 None
6）index(self, value, start=None, stop=None):
查找列表中value元素索引位置，start与stop参数是查找起始与结束位置，默认为None，返回int数值，如果查找中不包含这个元素，则返回ValueError: 'f' is not in list报错。
1 a=[1,2,3,4,5,6,7,'a','b','c'] 2 b=a.index('a') 3 print(a) 4 print(b) 5 6 #运行结果 7 [1, 2, 3, 4, 5, 6, 7, 'a', 'b', 'c'] 8 7
7）insert(self, index, p_object):
在列表index索引位置插入元素p_object，当index大于列表包含的元素个数时，在最后位置插入元素。
1 a=[1,2,3,4,5,6,7,'a','b','c'] 2 b=a.insert(1,'sb') 3 print(a) 4 print(b) 5 6 #运行结果 7 [1, 'sb', 2, 3, 4, 5, 6, 7, 'a', 'b', 'c'] 8 None
8）pop(self, index=None):
从列表中取出index位置的值，index默认为None，此时取出列表中最后一个值。
1 a=[1,2,3,4,5,6,7,'a','b','c'] 2 b=a.pop(7) 3 print(a) 4 print(b,type(b)) 5 6 #运行结果 7 [1, 2, 3, 4, 5, 6, 7, 'b', 'c'] 8 a <class 'str'>
9）remove(self, value):
移除列表中第一个出现的value元素，value元素不存在列表中时，则ValueError: list.remove(x): x not in list报错。
1 a=[1,2,3,4,5,6,7,'a','b','c'] 2 b=a.remove('a') 3 print(a) 4 print(b) 5 6 #运行结果 7 [1, 2, 3, 4, 5, 6, 7, 'b', 'c'] 8 None
10）reverse(self):
反转列表元素的位置。
1 a=[1,2,3,4,5,6,7,'a','b','c']
2 b=a.reverse()
3 print(a)
4 print(b)
5
6 #运行结果
7 ['c', 'b', 'a', 7, 6, 5, 4, 3, 2, 1]
8 None
11）sort(self, key=None, reverse=False):
给列表中的元素排序，key是指定取待排序元素的哪一项进行排序，默认为None，reverse实现降序排序，需要提供一个布尔值，默认为False（升序排列）。【sorted是生成个副本进行排序】
1 a=[1,2,8,9,5,6,7]
2 c=[2,7,3,9,1]
3 a.sort()
4 b=sorted(c)
5 print(a)
6 print(b)
7
8 #运行结果
9 [1, 2, 5, 6, 7, 8, 9]
10 [1, 2, 3, 7, 9]
12）切片[start:stop:step]
从列表中取出一部分元素生成一个新列表，start与stop默认为None，step表示步长值，默认是一个接着一个切取，如果为2,则表示进行隔一取一操作。步长值为正时表示从左向右取，如果为负，则表示从右向左取。步长值不能为0。
1 a=[1,2,8,9,5,6,7] 2 b=a[1:5:2] 3 c=a[:] 4 print(a) 5 print(b) 6 print(c) 7 8 #运行结果 9 [1, 2, 8, 9, 5, 6, 7] 10 [2, 9] 11 [1, 2, 8, 9, 5, 6, 7]
13) 索引list[index]
获取索引位置index的值。
1 a=['a','b','c','d'] 2 print(a[0]) 3 print(a[-1]) 4 5 #运行结果 6 a 7 d
13）__add__(self, *args, **kwargs):
列表添加一个新给出列表中的元素，生成一个新的列表。
1 a=[1,2,8,9,5,6,7] 2 b=a.__add__(['a',1]) 3 print(a) 4 print(b) 5 6 #运行结果 7 [1, 2, 8, 9, 5, 6, 7] 8 [1, 2, 8, 9, 5, 6, 7, 'a', 1]
14）__contains__(self, *args, **kwargs):
判断列表中是否包含某个元素，返回布尔值。
1 a=[1,2,8,9,5,6,7] 2 b=a.__contains__(2) 3 print(a) 4 print(b) 5 6 #运行结果 7 [1, 2, 8, 9, 5, 6, 7] 8 True