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Note: The test environment of this article is python2.7
Note: This article mainly introduces the general method of lists
Testing list
list1 = [1,2,3, 4]
insert method:
Method explanation: Insert the object at the specified position
Parameters:
Parameter 1: index
Parameter 2: object
Code example:
list1.insert(-1,1) #Insert object at the end of the list
list1.insert(0 ,1) #Insert object at the beginning of the list
Return value: None
Note: After the method is executed, the original list list1
pop method is directly modified :
Method explanation: Delete the element at the specified index
Parameters: If there is no parameter, the default is index -1 (the last member of the list)
Optional parameter one: index
Code example:
eg: s = list1.pop(1),s=list1[1] before deletion
Return value: deleted index Element
Note 1: When the index does not exist, an out-of-bounds error will be thrown
Note 2: The pop method can implement stack operations
eg:list1.append (list1.pop())
extend method:
Method explanation: Insert the sequence at the end of the list
Parameters:
Parameter 1: Sequence
Code example:
list2 = [1]
list1.extend(list2)
Return value: None
Note: Directly modify the original list list1, often used to connect lists, eg: list1 = list1+list2
index method:
Method explanation: return Specify the position where the element first appears in the list
Parameters:
Parameter 1: object
Parameter 2: startindex (optional, default 0)
Parameter 3: endindex (optional)
Code example:
list1[0] = 1
then list1.index(1) = 0
If you want to output the index of the specified position of the specified object, you need to use the other two parameters
index(objetc,startindex,endindex)
startindex start index
endindex End index
Note: When the object does not exist, an error will be thrown
append method:
Method explanation: Insert data at the end of the list
Parameter:
Parameter 1: object
Code example:
list1.append(1)
Return value: None
count method:
Method explanation: Returns the number of times the specified object appears in the list
Parameters:
Parameter 1: object
Code example:
ret = list1.count(11)
Return value: ret (int>=0)
Note: It can also be based on the number of returns = 0, to determine that the object is not in the list
remove method:
Method explanation: delete the object that appears first in the list
Parameters:
Parameter 1: object
Return value:
Code example:
list1.count(1)
Note 1: The When there are multiple elements, only the first one will be deleted
Note: When the object does not exist, an error will be thrown. It is best to use the count method and in to make the judgment
reverse method:
Method explanation: Reverse the original list
Parameters:
No parameters
Code example:
list1 .reverse()
Return value: No return value
Note: Directly modify list1 to reverse the sequence
Note: Built-in function reversed (object)
Parameter 1:
Sequence
Code example:
list1 = [1,2,3,4]
list2 = list(reversed(list1))
Return value: iterator
Note: The returned list2 is the reverse sequence of list1, but it will not affect the original sequence list1
Note 2: The effect after conversion is similar to list1[::-1]
sort method:
Method explanation: ascending sequence or Sort in descending order
Code example:
list1.sort()
Note: Sort list1 in ascending order
list1.sort (reverse=True)
Note: Sort list1 in descending order
Note: Built-in function sorted()
Method explanation: Return the original sequence Sorted sequence
Code example:
list2 = sorted(list1)
Note: Sorting in ascending order will not affect the original sequence list1
list2 = sorted(list1,reverse=True)
Note: Sorting in descending order will not affect the original required list1
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