Error demo
1 In [5]: a.extend([4,5]) 2 --------------------------------------------------------------------------- 3 AttributeError Traceback (most recent call last) 4 <ipython-input-5-42b5da5e2956> in <module> 5 ----> 1 a.extend([4,5]) 6 7 AttributeError: 'tuple' object has no attribute 'extend'
Print it tuple type of property you can see, tuple type in addition to built-in types, and index only count two properties
extend list type is a method
1 In [3]: dir(tuple) 2 Out[3]: 3 ['__add__', 4 '__class__', 5 '__contains__', 6 '__delattr__', 7 '__dir__', 8 '__doc__', 9 '__eq__', 10 '__format__', 11 '__ge__', 12 '__getattribute__', 13 '__getitem__', 14 '__getnewargs__', 15 '__gt__', 16 '__hash__', 17 '__init__', 18 '__init_subclass__', 19 '__iter__', 20 '__le__', 21 '. '__len__22 '__lt__', 23 '__mul__', 24 '__ne__', 25 '__new__', 26 '__reduce__', 27 '__reduce_ex__', 28 '__repr__', 29 '__rmul__', 30 '__setattr__', 31 '__sizeof__', 32 ''__str__, 33 '__subclasshook__', 34 'count', 35 'index']
extend a list is another list +,
It will change the length of the original list, but will not generate a new list
So, if you use a = list.extend (XXX), it will not if you want to return a list, but a None
Example:
1 In [6]: b=[1,2] 2 3 In [7]: c=b.extend([3]) 4 5 In [8]: b 6 Out[8]: [1, 2, 3] 9 10 In [10]: print(c) 11 None 12 13 In [11]: type(c) 14 Out[11]: NoneType
By the way:
statistics count represents the number of tuples in a specified elements appear
1 In [20]: b=(2,2,2,3,4) 2 3 In [21]: b.count(2) 4 Out[21]: 3
Returns the index of the position of the specified element occurs first (subscript)
1 In [20]: b=(2,2,2,3,4) 2 3 In [22]: b.index(3) 4 Out[22]: 3 5 6 In [23]: b.index(2) 7 Out[23]: 0
Attachment:
List all the properties as follows
1 In [4]: dir(list) 2 Out[4]: 3 ['__add__', 4 '__class__', 5 '__contains__', 6 '__delattr__', 7 '__delitem__', 8 '__dir__', 9 '__doc__', 10 '__eq__', 11 '__format__', 12 '__ge__', 13 '__getattribute__', 14 '__getitem__', 15 '__gt__', 16 '__hash__', 17 '__iadd__', 18 '__imul__', 19 '__init__', 20 '__init_subclass__', 21 ', '__iter__22 '__le__', 23 '__len__', 24 '__lt__', 25 '__mul__', 26 '__ne__', 27 '__new__', 28 '__reduce__', 29 '__reduce_ex__', 30 '__repr__', 31 '__reversed__', 32 ''__rmul__, 33 '__setattr__', 34 '__setitem__', 35 '__sizeof__', 36 '__str__', 37 '__subclasshook__', 38 'append', 39 'clear', 40 'copy', 41 'count', 42 'extend', 43 'index', 44 'insert', 45 'pop', 46 'remove', 47 'reverse', 48 'sort']
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