3. List method

list is similar to C + + in the Vector,c an array of languages used to store the sequential structure

Create a list ( List )

a=[' 1 ', ' 2 '] is enclosed in [] to denote a List, each element in the middle can be any type, separated by commas.

List structure

List function Splitting a string into a list

>>>list (' Chongshi ')
[' C ', ' H ', ' o ', ' n ', ' G ', ' s ', ' h ', ' I ']

Modifying a list : assigning values to an element

>>> x=[1,2,3,4]
>>> x[2]=18
>>> x
[1, 2, 18, 4]

Delete Element

>>> names = [' Zhangsan ', ' Lisi ', ' Wangwu ', ' Sunliu ']
>>> del names[2]
>>> names
[' Zhangsan ', ' Lisi ', ' Sunliu ']

Shard Assignment:

>>> name =list (' Huzi ')
>>> Name
[' H ', ' u ', ' z ', ' I ']
>>> name[2:]=list (' Dazhi ')
>>> Name
[' H ', ' u ', ' d ', ' a ', ' Z ', ' h ', ' I ']

The content of name is "Huzi", starting with the 3rd character (2), replacing "Zi" with "Da" and being expanded "zhi", so the content of the new name is "Hudazhi".

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List method

Object . Method (parameter)

1 , Append

The Append method is used to append a new object to the end of the list:

>>> ABC = [+]
>>> Abc.append (4)
>>> ABC
[1, 2, 3, 4]

2 , Count

Count method to count the number of occurrences of an element in a list:

>>>[' to ', ' being ', ' or ', ' not ', ' to ', ' being ',].count (' to ')
2
>>> x = [[1,2],1,1,[2,1,[1,2]]
>>> x.count (1)    
2
>>> X.count ([up])
1

3, Extend

The Extend method can append multiple values from another sequence at the end of the list at once. To extend an existing list with a new list:

>>>a = [A]
>>> B = [4,5,6]
>>> A.extend (b)
>>> A
[1, 2, 3, 4, 5, 6]

4. Index

The index method is used to find the first occurrence of a value from a list.

>>>knights = [' We ', ' is ', ' the ', ' kninghts ', ' who ', ' say ', ' ni ']
>>> Knights.index (' Who ')
4
>>> Knights[4]
' Who '

5. Insert

The Insert method is used to insert an object into the list:

>>> numbers = [1,2,3,5,6,7]
>>> Numbers.insert (3, ' four ') # inserted in front
>>> numbers
[1, 2, 3, ' Four ', 5, 6, 7]

6. Pop

The Pop method removes an element from the list (the last one by default) and returns the value of the element:

>>>x = [A]
>>> X.pop ()
3
>>> x
[1, 2]
>>> X.pop (0)
1
>>> x
[2]

Analog compression, stack

>>>a=[]

>>> a.append (0)        # Press Stack

>>>a.append (1)

>>>a.append (2)

>>>a

[0, 1, 2]

>>> A.pop ()                  # out of the stack

2

>>>a.pop ()

1

>>>a.pop ()

0

Analog Queues

>>> A.insert (0,0)    # Queue

>>>a.insert (0,1)

>>>a.insert (0,2)

>>>a

[2, 1, 0]

>>> A.pop ()             # out Team

0

>>>a.pop ()

1

>>>a.pop ()

2

>>>a

[]

Or:

>>> a.append (0)         # Queue

>>>a.append (1)

>>>a.append (2)

>>>a

[0, 1, 2]

>>> a.pop (0)                # out Team

0

>>>a.pop (0)

1

>>>a.pop (0)

2

>>>a

[]

7. Remove

The Remove method is used to remove the first occurrence of a value in the list: # no return value, opposite of pop

>>>x = [' to ', ' is ', ' or ', ' not ', ' to ', ' being ']
>>> x.remove (' be ')
>>> x
[' to ', ' or ', ' no ', ' to ', ' being ']

8, Reverse

The Revers method stores the elements in the list in reverse

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

This can also be achieved:

>>> List (reversed (x))

[3, 2, 1]

9. Sort

The sort method is used to sort the list at the original location. "Sort in place" changes the original list so that the elements can be sorted in a certain order (no return value).

>>>x = [4,6,2,1,7,9]
>>> X.sort ()
>>> x
[1, 2, 4, 6, 7, 9]

>>> x = [4,6,2,1,7,9]
>>> y = x # copy sort
>>> Y.sort ()

>>>y

[1, 2, 4, 6, 7, 9]

# another way to sort replicas

>>>x = [4,6,2,1,7,9]
>>> y = sorted (x)

>>>y

[1, 2, 4, 6, 7, 9]

>>>x

[4, 6, 2, 1, 7, 9]

Sorted can be used for any sequence

>>>sorted (' python ')

[' H ', ' n ', ' o ', ' P ', ' t ', ' Y ']

Ten , Advanced sorting

List de-weight: {}.fromkeys (list). Keys () List character sort: List.sort (key=int) list.sort (Key=len) #指定排序键类型 l Ist.sort (reverse=true) #反向排序

From for notes (Wiz)

3. List method