Detailed introduction to lists and tuples in python-Python Tutorial-php.cn

Detailed introduction to lists and tuples in python

高洛峰

Release： 2017-03-08 11:36:17

Original

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Common operations: indexing, sharding, addition, multiplication, checking whether an element is a member of the sequence, length, minimum value, maximum value

Example:

numbers=[100,34,67]

len(numbers) #返回值为3max(numbers) #返回值为100min(numbers) #返回值为34

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List：

1. List function

>>>list('Hello')
['H','e','l','l','o']

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*You can use join (For example: ''.join(somelist)) Convert the composed list into a string

2. List operations

Element assignment:

>>>x=[1,2,3]>>>x[1]=4
>>>x
[1,4,3]

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Delete element:

>>>x=['abc','def','ghi','jk']>>>del x[2]>>>x
['abc','def','jk']

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Slice assignment:

>>>x=list('Happy')>>>name
['H','a','p','p','y']>>>x[1:]=list('ello')>>>x
['H','e','l','l','o']

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3. List method:

append

>>>x=[1,2,3]>>>x.append(4)>>>x
[1,2,3,4]

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count

>>>x=[1,2,3,1,3,5,5]>>>x.count(3)2

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extend

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

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index

>>>x=['a','b','c']
>>>x.index('b')
1

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insert Insert element

>>>x=[1,2,3]
>>>x.insert(2,'a')
>>>x
[1,2,'a',3]

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pop Remove the list element (default last)

>>> x=[1,2,3,4]>>> x.pop()4
>>> x.pop(1)2
>>> x
[1, 3]

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remove Remove from the list The first match of a value

>>> x=['my','to','is','she','to']>>> x.remove('to')>>> x
['my', 'is', 'she', 'to']

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reverse Store the elements in the list in reverse

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

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>>> x=[1,2,3]>>> list(reversed(x))
[3, 2, 1]>>> x
[1, 2, 3]

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sort is used to sort the list at the original position

>>> x=[4,6,2,1,7,8,3]>>> x.sort()>>> x
[1, 2, 3, 4, 6, 7, 8]>>> x=[4,6,2,1,7,8,3]>>> y=sorted(x)>>> x
[4, 6, 2, 1, 7, 8, 3]>>> y
[1, 2, 3, 4, 6, 7, 8]>>> x=[3,2,1]>>> y=x>>> y.sort()>>> x
[1, 2, 3]>>> y
[1, 2, 3]

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>> ;> sorted('hello')
['e', 'h', 'l', 'l', 'o']

Tuple: cannot be changed Sequence

>>> 1,2,3(1, 2, 3)>>> (1,2,3)
(1, 2, 3)>>> () #空元组()>>> 1，
SyntaxError: invalid syntax>>> 1,
(1,)>>> 1, #元祖必须有逗号(1,)>>> 3*(40+2,)
(42, 42, 42)

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tuple function converts the sequence into a tuple

>>> tuple([3,2,1])
(3, 2, 1)>>> tuple('abc')
('a', 'b', 'c')

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The reason why tuples are not fungible

Tuples can be used as keys in maps
Tuples are used as many built-in functions and the return value of the method exists

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