Detailed explanation of lists and tuples in python

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

Example:

<p style="margin-bottom: 7px;">numbers=[100,34,67]<br/>len(numbers) #返回值为3max(numbers) #返回值为100min(numbers) #返回值为34</p>

List :

1. List function

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

*You can use join (for example: ''.join(somelist)) to convert the composed list into a string

2. List operations

Element assignment:

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

Delete element:

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

Slice assignment:

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

3. List method:

append

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

count

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

extend

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

index

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

insert insert element

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

pop remove list Element (default last)

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

remove Remove the first matching item of a value in the list

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

reverse Store the elements in the list in reverse order

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

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

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]

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

Tuple: immutable 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)

tuple function converts the sequence into a tuple

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

The reason for the irreplaceability of tuples

• Tuples can be used as keys in maps

• Tuples as many The return values ​​of built-in functions and methods exist

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