Python | Slicing list from Kth element to last element

Python list slicing slices the list from start index till end – 1, specified as list elements. So its tricky when we require to also slice the last element of list. Trying to slice till list size + 1 gives an error. Let’s discuss ways in which last element can be included during a list slice. 
Method #1 : Using None During list slicing, giving the desired first index K and specifying ‘None’ as the second argument in slicing works internally as slicing all the elements from K in list till end including it. 

Python3

# Python3 code to demonstrate
# list slicing from K to end
# using None

# initializing list
test_list = [5, 6, 2, 3, 9]

# printing original list
print ("The original list is : " + str(test_list))

# index to begin slicing
K = 2

# using None
# to perform list slicing from K to end
res = test_list[K : None]

# printing result
print ("The sliced list is : " +  str(res))

Output:

The original list is : [5, 6, 2, 3, 9]
The sliced list is : [2, 3, 9]

Method #2 : Leaving the last element empty Usually, not specifying any element as end element of slicing instructs python to include whole list after K in list. But the main drawback in using this is code readability. Hence above method is preferred more than this. 

Python3

# Python3 code to demonstrate
# list slicing from K to end
# without specifying last element

# initializing list
test_list = [5, 6, 2, 3, 9]

# printing original list
print ("The original list is : " + str(test_list))

# index to begin slicing
K = 2

# without specifying last element
# to perform list slicing from K to end
res = test_list[K :]

# printing result
print ("The sliced list is : " +  str(res))

Output:

The original list is : [5, 6, 2, 3, 9]
The sliced list is : [2, 3, 9]

Method #3 : Using itertools

Here is an example of using the islice() function from the itertools module to slice a list from the Kth element to the last element:

Python3

from itertools import islice

# Initialize the list
test_list = [5, 6, 2, 3, 9]

# Index to begin slicing
K = 2

# Use islice() to slice the list from the Kth element to the last element
res = list(islice(test_list, K, None))

print(res)  # [2, 3, 9]
#This code is contributed by Edula Vinay Kumar Reddy

Output

[2, 3, 9]

Time complexity: O(n)

Auxiliary space: O(n)