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Python | Remove all occurrences in nested list

  • Last Updated : 16 May, 2019
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The task of removal of element generally doesn’t pose any challenge, but sometimes, we may have a more complex problem than just removing a single element or performing removal in just a normal list. Problem can be removing all occurrences of nested list. Let’s discuss certain ways in which this problem can be solved.

Method #1 : Using list comprehension

The list comprehension can be used as a shorter method to the recommended longer method in normal way of loops to perform this task in which we just check for a match and reconstruct the list without the target list element.




# Python3 code to demonstrate
# Remove all occurrences in nested list
# using list comprehension
  
# initializing list
test_list = [[4, 5], [1, 2, 3], [4, 5], [8, 9], [10, 11]]
  
# initializing list to delete
del_list = [4, 5]
  
# printing original list
print("The original list : " + str(test_list))
  
# printing delete list 
print("The list to be deleted is : " + str(del_list))
  
# using list comprehension
# Remove all occurrences in nested list
res = [i for i in test_list if i != del_list]
  
# print result
print("The list after removal of list element : " + str(res))
Output :
The original list : [[4, 5], [1, 2, 3], [4, 5], [8, 9], [10, 11]]
The list to be deleted is : [4, 5]
The list after removal of list element : [[1, 2, 3], [8, 9], [10, 11]]

 



Method #2 : Using filter() + partial() + operator.ne

The task can also be performed using the above functions. The filter function performs filtering, and returns the partial list by partial function and not equal condition is imposed using the operator.ne method.




# Python3 code to demonstrate
# Remove all occurrences in nested list
# using filter() + partial() + operator.ne
from functools import partial
from operator import ne
  
# initializing list
test_list = [[4, 5], [1, 2, 3], [4, 5], [8, 9], [10, 11]]
  
# initializing list to delete
del_list = [4, 5]
  
# printing original list
print("The original list : " + str(test_list))
  
# printing delete list 
print("The list to be deleted is : " + str(del_list))
  
# using filter() + partial() + operator.ne
# Remove all occurrences in nested list
res = list(filter(partial(ne, del_list), test_list))
  
# print result
print("The list after removal of list element : " + str(res))
Output :
The original list : [[4, 5], [1, 2, 3], [4, 5], [8, 9], [10, 11]]
The list to be deleted is : [4, 5]
The list after removal of list element : [[1, 2, 3], [8, 9], [10, 11]]

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