How to delete elements from a list in python

How to delete elements in a list in python: 1. Use remove() to delete a single element. This function can delete the first matching item of a certain value in the list; 2. Use pop() to delete a single or multiple elements. element, this function deletes the element based on the index and returns the value of the element; 3. Use the del keyword to delete the element based on the index.

The operating environment of this tutorial: windows7 system, python3 version, DELL G3 computer

In python, about deleting an element in the list, generally There are three methods: remove, pop, del:

1.remove: Delete a single element, delete the first element that meets the conditions, delete by value
Example:

>>> str=[1,2,3,4,5,2,6]
>>> str.remove(2)
>>> str

Output

[1, 3, 4, 5, 2, 6]

2.pop: Delete single or multiple elements, bitwise deletion (delete based on index)

>>> str=[0,1,2,3,4,5,6]
>>> str.pop(1) #pop删除时会返回被删除的元素
>>> str
[0, 2, 3, 4, 5, 6]

>>> str2=['abc','bcd','dce']
>>> str2.pop(2)
'dce'
>>> str2
['abc', 'bcd']

3.del : It deletes based on the index (the location of the element)

Example:

>>> str=[1,2,3,4,5,2,6]
>>> del str[1]
>>> str
[1, 3, 4, 5, 2, 6]

>>> str2=['abc','bcd','dce']
>>> del str2[1]
>>> str2
['abc', 'dce']

In addition, del can also delete values ​​within the specified range.

>>> str=[0,1,2,3,4,5,6]
>>> del str[2:4] #删除从第2个元素开始，到第4个为止的元素(但是不包括尾部元素)
>>> str
[0, 1, 4, 5, 6]

del can also delete the entire data object (list, collection, etc.)

>>> str=[0,1,2,3,4,5,6]
>>> del str
>>> str #删除后，找不到对象
Traceback (most recent call last):
File "8052ae779430ccf893a6c66dd5fa83ea", line 1, in 4225fa317875f3e92281a7b1a5733569
str
NameError: name 'str' is not defined

Note: del deletes the reference (variable) instead of deleting the object (data). The object is collected by the automatic garbage collection mechanism (GC) deleted.

Supplement: Disguised method of deleting elements

s1 = (1, 2, 3, 4, 5, 6)
s2 = (2, 3, 5)
s3 = []for i in s1:    if i not in s2:
        s3.append(i)print('s1_1:', s1)
s1 = s3print('s2:', s2)print('s3:', s3)print('s1_2:', s1)

Related recommendations: Python3 video tutorial

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