Python学习笔记(一):list属性及方法浅析
【摘要】 列表学习。
List是python中的基本数据结构之一。创建一个列表的方法
L = [1,2,3,'a']
通过help(list)查看列表的属性及方法。
>>> help(list)
Help on class list in module builtins:
class list(object)
| ...
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In [1]: a = list()
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In [2]: a
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Out[2]: []
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In [6]: s = "hello world!"
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In [7]: L = list(s)
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In [8]: L
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Out[8]: ['h', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '!']
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In [1]: a = [1,2]
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In [2]: b = [1,2]
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In [3]: a.__add__(b) # 返回a+b，a,b本身没有改变
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Out[3]: [1, 2, 1, 2]
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In [4]: a
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Out[4]: [1, 2]
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In [5]: b
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Out[5]: [1, 2]
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In [6]: c = a.__add__(b)
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In [7]: c
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Out[7]: [1, 2, 1, 2]
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In [8]: d = a+b
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In [9]: c == b
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Out[9]: False
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In [10]: c == d
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Out[10]: True
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In [11]: L = [1,2,3,4]
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In [12]: L.__contains__(1)
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Out[12]: True
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In [13]: L.__contains__(2)
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Out[13]: True
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In [14]: L.__contains__(0)
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Out[14]: False
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In [15]: L.__contains__('a')
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Out[15]: False
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In [16]: L.__contains__(L) #并不包含本身
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Out[16]: False
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In [18]: L in L
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Out[18]: False
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In [19]: 2 in L
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Out[19]: True
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In [20]: 0 in L
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Out[20]: False
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In [21]: L = [1,2,3]
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In [22]: L.__delitem__(0) #删除第0个对象
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In [23]: L
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Out[23]: [2, 3]
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In [24]: del L[1] #删除第1个对象
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In [25]: L
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Out[25]: [2]
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In [36]: a = [1,2,3,4]
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In [37]: b = [1,2]
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In [38]: a.__eq__(1)
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Out[38]: NotImplemented #没有实现该功能
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In [39]: a.__eq__([1,2])
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Out[39]: False
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In [40]: a.__eq__(b)
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Out[40]: False
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In [41]: a.__eq__([1,2,3,4])
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Out[41]: True
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In [42]: a.__eq__((1,2,3,4))
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Out[42]: NotImplemented
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与 == 略有差异
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In [43]: a = [1,2,3,4]
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In [44]: b = [1,2]
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In [45]: a == 1
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Out[45]: False
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In [46]: a == [1,2]
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Out[46]: False
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In [47]: a == [1,2,3,4]
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Out[47]: True
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In [48]: a == b
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Out[48]: False
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In [49]: a == (1,2,3,4)
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Out[49]: False
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In [63]: a = [1,2,3,4]
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In [64]: a.__getattribute__('__len__')
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Out[64]: <method-wrapper '__len__' of list object at 0x02558EE0>
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In [65]: b = a.__getattribute__('__len__')
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In [66]: b()
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Out[66]: 4
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In [67]: a
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Out[67]: [1, 2, 3, 4]
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In [68]: a.__getattribute__('copy')
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Out[68]: <function list.copy>
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In [69]: b = a.__getattribute__('copy')
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In [70]: c = b()
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In [71]: c
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Out[71]: [1, 2, 3, 4]
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In [1]: a = [1,2,3,"hello",(1,2,3)]
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In [2]: a.__getitem__(0)
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Out[2]: 1
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In [3]: a.__getitem__(3)
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Out[3]: 'hello'
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In [4]: a.__getitem__(4)
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Out[4]: (1, 2, 3)
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In [5]: a.__getitem__(5) 无法访问越界的对象
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---------------------------------------------------------------------------
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IndexError Traceback (most recent call last)
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<ipython-input-5-3a58e3eacf6a> in <module>()
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----> 1 a.__getitem__(5)
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IndexError: list index out of range #越界报错
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In [6]: a = [1,2,3,"hello",(1,2,3)]
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In [7]: a[0]
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Out[7]: 1
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In [8]: a[3]
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Out[8]: 'hello'
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In [9]: a[4]
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Out[9]: (1, 2, 3)
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In [10]: a[5]
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---------------------------------------------------------------------------
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IndexError Traceback (most recent call last)
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<ipython-input-10-b6a934feab86> in <module>()
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----> 1 a[5]
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IndexError: list index out of range
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In [3]: a = [1,2,3,4]
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In [4]: a.__iadd__("hello")
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Out[4]: [1, 2, 3, 4, 'h', 'e', 'l', 'l', 'o'] #先将字符串转换为列表，然后再相加，列表会改变
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In [5]: a.__iadd__((1,2,3))
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Out[5]: [1, 2, 3, 4, 'h', 'e', 'l', 'l', 'o', 1, 2, 3] #先将元组转换为列表，然后再相加，列表会改变
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In [6]: a.__iadd__([1111,1113]) #列表相加，列表会改变
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Out[6]: [1, 2, 3, 4, 'h', 'e', 'l', 'l', 'o', 1, 2, 3, 1111, 1113]
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In [7]: a #a已改变
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Out[7]: [1, 2, 3, 4, 'h', 'e', 'l', 'l', 'o', 1, 2, 3, 1111, 1113]
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In [15]: a = [1,2,3,'abc']
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In [16]: a.__imul__(2) #*2并返回给a
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Out[16]: [1, 2, 3, 'abc', 1, 2, 3, 'abc']
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In [17]: a #a已改变
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Out[17]: [1, 2, 3, 'abc', 1, 2, 3, 'abc']
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In [18]: a.__imul__([1,2]) #参数不是integer类型，报错
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---------------------------------------------------------------------------
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TypeError Traceback (most recent call last)
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<ipython-input-18-58ca78754a99> in <module>()
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----> 1 a.__imul__([1,2])
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TypeError: 'list' object cannot be interpreted as an integer
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In [23]: a = []
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In [24]: b = [1,2,3,4]
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In [25]: a.__init__(b)
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In [26]: a
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Out[26]: [1, 2, 3, 4]
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In [27]: a.__init__((1,2,3)) #先将元组转换为列表，再初始化给a
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In [28]: a
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Out[28]: [1, 2, 3]
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In [34]: a = [1,2,3,4,54]
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In [35]: for i in a.__iter__():
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...: print (i)
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...:
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1
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2
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3
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4
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54
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In [36]: a.__iter__
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Out[36]: <method-wrapper '__iter__' of list object at 0x024B7D00>
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In [37]: a.__iter__() #列表类型的迭代器
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Out[37]: <list_iterator at 0x25586b0>
__le__(self, value, /) Return self<=value. 判断列表是不大于某列表。与__eq__类似
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In [38]: a = [1,2,3,"abc",(111,222,333)]
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In [39]: a.__len__()
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Out[39]: 5
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In [40]: a.__len__
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Out[40]: <method-wrapper '__len__' of list object at 0x024C44B8>
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In [41]: a = [1,2,3,"abc",(111,222,333)]
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In [42]: a.__mul__(2)
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Out[42]: [1, 2, 3, 'abc', (111, 222, 333), 1, 2, 3, 'abc', (111, 222, 333)]
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In [43]: a
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Out[43]: [1, 2, 3, 'abc', (111, 222, 333)]
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In [1]: a = [1,2,3,4]
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In [2]: b = a.__new__(list)
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In [3]: b
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Out[3]: []
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In [4]: b = a.__new__(str)
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---------------------------------------------------------------------------
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TypeError Traceback (most recent call last)
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<ipython-input-4-6fee1f0c3d80> in <module>()
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----> 1 b = a.__new__(str)
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TypeError: list.__new__(str): str is not a subtype of list
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In [5]: b = a.__new__(tuple)
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---------------------------------------------------------------------------
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TypeError Traceback (most recent call last)
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<ipython-input-5-18991a398a58> in <module>()
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----> 1 b = a.__new__(tuple)
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TypeError: list.__new__(tuple): tuple is not a subtype of list
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In [12]: a = [1,2,3,4]
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In [13]: b = a.__repr__()
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In [14]: b
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Out[14]: '[1, 2, 3, 4]' #字符串
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In [15]: a
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Out[15]: [1, 2, 3, 4]
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In [19]: a = [1,2,3,4]
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In [20]: a.__reversed__()
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Out[20]: <list_reverseiterator at 0x2538c50>
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In [21]: a
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Out[21]: [1, 2, 3, 4]
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In [22]: b = a.__reversed__()
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In [23]: for i in b:
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...: print (i)
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...:
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4
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3
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2
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1
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In [34]: a = [1,2,3,4,"abc"]
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In [35]: a.__mul__(-1)
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Out[35]: []
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In [36]: a.__mul__(0)
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Out[36]: []
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In [37]: a
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Out[37]: [1, 2, 3, 4, 'abc']
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In [38]: a.__mul__(2)
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Out[38]: [1, 2, 3, 4, 'abc', 1, 2, 3, 4, 'abc']
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In [39]: a
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Out[39]: [1, 2, 3, 4, 'abc']
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In [40]: a.__setitem__(2,"aaa")
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In [41]: a
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Out[41]: [1, 2, 'aaa', 4, 'abc']
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In [43]: a
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Out[43]: [1, 2, 3, 4, 'abc']
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In [44]: a = []
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In [45]: a.__sizeof__
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Out[45]: <function list.__sizeof__>
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In [46]: a.__sizeof__()
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Out[46]: 20
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In [47]: a = [1]
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In [48]: a.__sizeof__()
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Out[48]: 24
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In [49]: a = [1,2,3]
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In [50]: a.__sizeof__()
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Out[50]: 32
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In [51]: a = ['a']
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In [52]: a.__sizeof__()
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Out[52]: 24
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In [53]: a = ['abc']
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In [54]: a.__sizeof__()
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Out[54]: 24
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In [55]: a = [1]
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In [56]: a.append(2)
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In [57]: a
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Out[57]: [1, 2]
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In [58]: a.append('2')
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In [59]: a
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Out[59]: [1, 2, '2']
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In [60]: a.append([1,2])
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In [61]: a
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Out[61]: [1, 2, '2', [1, 2]]
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In [62]: a.append((3,4))
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In [63]: a
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Out[63]: [1, 2, '2', [1, 2], (3, 4)]
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In [64]: a
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Out[64]: [1, 2, '2', [1, 2], (3, 4)]
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In [65]: a.clear()
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In [66]: a
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Out[66]: []
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In [67]: a = [1,2,3,4]
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In [68]: b = a.copy()
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In [69]: a
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Out[69]: [1, 2, 3, 4]
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In [70]: b
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Out[70]: [1, 2, 3, 4]
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In [71]: a = [1,2,3,'a','aa',[1,2]]
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In [72]: a.count(1)
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Out[72]: 1
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In [73]: a.count('a')
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Out[73]: 1
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In [74]: a.count([1,2])
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Out[74]: 1
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In [75]: a.count(0)
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Out[75]: 0
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In [80]: a = [1,2,3]
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In [81]: a.extend((1,2,3))
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In [82]: a
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Out[82]: [1, 2, 3, 1, 2, 3]
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In [83]: a.extend([4,5,6])
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In [84]: a
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Out[84]: [1, 2, 3, 1, 2, 3, 4, 5, 6]
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In [85]: a
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Out[85]: [1, 2, 3, 1, 2, 3, 4, 5, 6]
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In [86]: a.index(2)
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Out[86]: 1 #返回第一个出现对象的位置
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In [87]: a.index(7) #列表中不存在是时报错
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---------------------------------------------------------------------------
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ValueError Traceback (most recent call last)
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<ipython-input-87-e64802c95647> in <module>()
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----> 1 a.index(7)
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ValueError: 7 is not in list
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In [90]: a.insert(0,"abc")
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In [91]: a
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Out[91]: ['abc', 1, 2, 3, 1, 2, 3, 4, 5, 6]
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In [92]: a.pop(2)
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Out[92]: 2
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In [93]: a
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Out[93]: ['abc', 1, 3, 1, 2, 3, 4, 5, 6]
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In [100]: a = [1,1,2,2,3,3,4,4,"aa",'aa']
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In [101]: a.remove(1)
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In [102]: a
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Out[102]: [1, 2, 2, 3, 3, 4, 4, 'aa', 'aa']
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In [103]: a.remove('aa')
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In [104]: a
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Out[104]: [1, 2, 2, 3, 3, 4, 4, 'aa']
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In [105]: a = [1,2,3]
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In [106]: a.reverse()
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In [107]: a
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Out[107]: [3, 2, 1]
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In [112]: a = [1,9,2,3,7,4]
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In [113]: a.sort()
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In [114]: a
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Out[114]: [1, 2, 3, 4, 7, 9]
文章来源: blog.csdn.net，作者：悦来客栈的老板，版权归原作者所有，如需转载，请联系作者。
原文链接：blog.csdn.net/qq523176585/article/details/77978925
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