Python | Remove last K elements of list

We often come to the situations in which we need to decrease the size of the list by truncating the k last elements of the list. This particular problem occurs when we need to optimize memory. This has its application in the day-day programming when sometimes we require to get all the lists of similar size. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using len() + list slicing
List slicing can perform this particular task in which we just slice the first len(list) – K elements to be in the list and hence removing the last K elements.

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# Python code to demonstrate 
# remove last K elements
# using len() + list slicing
  
# initializing list  
test_list = [1, 4, 6, 3, 5, 8]
  
# printing original list
print ("The original list is : " + str(test_list))
  
# initializing K 
K = 3
  
# using len() + list slicing
# remove last K elements
res = test_list[: len(test_list) - K]
  
# printing result 
print ("The list after removing last K elements : " +  str(res))

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Output:



The original list is : [1, 4, 6, 3, 5, 8]
The list after removing last K elements : [1, 4, 6]

 
Method #2 : Using Negative list slicing
We can perform this particular task using the negative list slicing in which we start removing the elements from the last index of the list and hence remove all the K elements from the last. We remove None if 0 elements are asked to be removed.

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# Python code to demonstrate 
# remove last K elements
# using negative list slicing
  
# initializing list  
test_list = [1, 4, 6, 3, 5, 8]
  
# printing original list
print ("The original list is : " + str(test_list))
  
# initializing K 
K = 3
  
# using negative list slicing
# remove last K elements
res = test_list[: -K or None]
  
# printing result 
print ("The list after removing last K elements : " +  str(res))

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Output:

The original list is : [1, 4, 6, 3, 5, 8]
The list after removing last K elements : [1, 4, 6]


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