Python Tutorial: Three Ways to Delete List Elements

In Python, there are generally three methods for deleting an element in a list: 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
[1, 3, 4, 5, 2, 6]

2.pop: Delete single or multiple elements, delete by bit (according to Index deletion)

>>> 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 is deleted based on the index (location of the element)

Example:

>>> str=[1,2,3,4,5,2,6]
>>> str2.pop(2)
[1, 3, 4, 5, 2, 6]
>>> str2=['abc','bcd','dce']
>>> del str2[1]
>>> str2
['abc', 'dce']

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

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>>> 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 "<pyshell#27>", line 1, in <module>
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

print('s1_2:', s1)
's3:', s3)
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 = s3
print('s2:', s2)
print('s3:', s3)
print('s1_2:', s1)

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