A common approach to the list of Python sequences

Note: This test environment is python2.7

Note: This article mainly introduces the general method of the list

Test List

List1 = [1,2,3,4]

Insert Method:

Method Explanation: Inserting an object at a specified location

Parameters:

Parameter 1:index

Parameter 2:object

code example:

List1.insert ( -1,1) #在列表末尾插入对象

List1.insert (0,1) #在列表开头插入对象

return value: None

Note: After the method executes, directly modifies the original list List1

Pop method:

Method Explanation: Delete the element of the specified index

Parameter: Default is index-1 (last member of list) without parameter

Optional parameter one: index

code example:

Eg:s = List1.pop (1), s= before deletion list1[1]

Return value: The element at the index being deleted

Note 1: A cross-border error is thrown when the index does not exist

Note the 2:pop method can implement the operation of the stack

Eg:list1.append (List1.pop ())

Extend method:

Method explanation: Inserting a sequence at the end of a list

Parameters:

Parameter one: sequence

code example:

List2 = [1]

List1.extend (LIST2)

return value: None

Note: Modify the original list List1 directly, commonly used for connection list, Eg:list1 = List1+list2

Index method:

Method Explanation: Returns the position where the specified 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 at the specified position of the specified object, you need to use two additional parameters

Index (OBJETC,STARTINDEX,ENDINDEX)

startindex Start Index

Endindex End Index

Note: An error is thrown when the object does not exist

Append method:

Method Explanation: Inserting data at the end of the list

Parameters:

Parameter 1:object

code example:

List1.append (1)

return value: None

Count Method:

Method Explanation: Returns the number of occurrences of the specified object in the list

Parameters:

Parameter 1:object

code example:

ret = List1.count (11)

return value: Ret (int>=0)

Note: It is also possible to determine if the object is not in the list, depending on the number of returns = 0

Remove method:

Method Explanation: Delete the first occurrence of the object in the list

Parameters:

Parameter 1:object

return value:

code example:

List1.count (1)

Note 1: When the element has multiple, only the first one is deleted

Note: When an object does not exist, it throws an error, preferably with the count method and in to determine

Reverse method:

Method Explanation: Invert the original list

Parameters:

No reference

code example:

List1.reverse ()

Return value: no return value

Note: Modify the List1 directly 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 an inverted sequence of list1, but does not affect the original sequence List1

Note 2: The effect after conversion is similar to list1[::-1]

Sort method:

Method Explanation: Sort the sequence in ascending or descending order

code example:

List1.sort ()

Note: The list1 is sorted in ascending order

List1.sort (Reverse=true)

Note: The list1 is sorted in descending order

Note: Built-in function sorted ()

Method Explanation: Returns the sequence after the original sequence is sorted

code example:

List2 = sorted (List1)

Note: Ascending arrangement does not affect the original sequence List1

List2 = sorted (list1,reverse=true)

Note: The descending arrangement does not affect the original need List1