Remove first element from list in Python

The task of removing the first element from a list in Python involves modifying the original list by either deleting, popping, or slicing the first element. Each method provides a different approach to achieving this. For example, given a list a = [1, 2, 3, 4], removing the first element results in [2, 3, 4].

Using del keyword

del statement is a direct way to remove the first element from a list. It modifies the original list in place, making it a simple and efficient approach for removing elements without creating a new list.

a = [1, 2, 3, 4]

del a[0]
print(a)

[2, 3, 4]

Explanation: del a[0] removes the first element, shifting the remaining elements left and updating the list in place.

Using pop()

pop(0) method removes and returns the first element of the list. This is useful when we need to capture the removed element while modifying the list.

a = [1, 2, 3, 4]

a.pop(0)
print(a)

[2, 3, 4]

Explanation: a.pop(0) removes and returns the first element of the list, shifting the remaining elements left. The list is updated in place and the removed element is no longer part of the list.

Using slicing

Slicing creates a new list starting from the second element, effectively removing the first element. It's a concise way to remove the first element, especially when we don't mind creating a new list.

a = [1, 2, 3, 4]

a = a[1:]
print(a)

[2, 3, 4]

Explanation: slicing a[1:] creates a new list starting from the second element, effectively removing the first element and assigning the result back to a.

Using collections.deque

deque from the collections module is designed for efficient removal of elements from both ends of a list. If we frequently need to remove the first element, this is the best option as it optimizes such operations.

from collections import deque

a = deque([1, 2, 3, 4])
a.popleft()
print(a)

deque([2, 3, 4])

Explanation: a.popleft() removes and returns the first element from the deque, efficiently updating the deque in place by shifting the remaining elements to the left.