list mothod总结(python3.5)

1. 创建一个空的list

>>>a = []
>>>a = list()

2. L.append(object)

append用于在list末尾追加一个新的对象，改变list本身

>>>a = []
>>>a.append(2)
>>>a
[2]
>>>a.append([3,4])
>>>a
[2,[3,4]]

3. L.extend(iterable)

extend可以在list的末尾追加另一个序列中的多个值

>>>a = [1,2,3]
>>>b = [4,5,6]
>>>a.extend(b)
>>>a
[1,2,3,4,5,6]
>>> member = [1,2,3]
>>> member.extend((4,5,6))
>>> member
[1, 2, 3, 4, 5, 6]    #可以将tuple里面的元素追加到list

与连接不同的是：extend方法改变了被扩展的list

>>>a = [1,2,3]
>>>b = [4,5,6]
>>>a + b
[1,2,3,4,5,6]
>>>a
[1,2,3]

4. L.insert(index, object)

insert用于将对象插入index之后,改变list本身

>>>numbers = [1,2,3,4,5]
>>>numbers.insert(0,'start')
>>>numbers
['start',1,2,3,4,5]
>>>len(numbers)
6
#当index>len(list)时，自动插入到最后
>>>a = [1, 2, 3]
>>>a.insert(4,4)
>>>a
[1, 2, 3, 4]
>>>a.insert(-5, -1)
>>>a
[-1, 1, 2, 3, 4]

5. L.pop()

pop用于移除list中的一个元素(默认最后一个),并且返回该元素
可指定位置,不存在的位置会报错

>>>a = [1,2,3]
>>>a.pop()
3
>>>a
[1,2]
>>>a.pop(0)
a
>>>a
[2]
>>>a.pop(100)
IndexError: pop index out of range

6. L.remove()

remove用于移除list中某个值的第一个匹配项
没有返回错误

>>>a = ['we','you','me','to','you']
>>>a.remove('me')
>>>a
['we', 'you', 'to', 'you']
>>>a.remove('you')
>>>a
['we','to','you']
>>>a.remove(3)
ValueError: list.remove(x): x not in list

7. L.count(value)

count用来统计某个元素在list中出现的次数
不存在则返回0

>>>a = [1,2,3,4,5,1]
>>>a.count(1)
2
>>>a.count(2)
1
>>>a.count(0)
0

8. L.index(value, [start, [stop]])

index返回某个值在list中第一次出现的索引

>>>a = [1,2,3,1,2,3]
>>>a.index(2)
1
#当这个值不在list中的时候,会触发一个异常
>>>a.index(0)
ValueError: 0 is not in list

9. L.reverse()

reverse将list中的元素反向存放,改变list本身

>>>a = [1,2,3]
>>>a.reverse()
>>>a
[3,2,1]

10. L.sort()

sort将list进行排序,改变list本身

>>>a = [3,-1,4,-3,7,2,0]
>>>a.sort()
>>>a
[-3, -1, 0, 2, 3, 4, 7]

11.L.clear()

清空

>>>a = [1, 2, 3, 4]
>>>a.clear()
>>>a
[]