Is There a More Efficient Way to Rotate Python Lists Than Concatenation?

Efficient Rotation of Python Lists

Rotating a list involves shifting its elements by a specified number of positions to the left or right. A common approach, as shown in the provided code, is to concatenate the necessary portions of the original list. However, is there a more efficient method?

Leveraging Collections.deque

Collections.deque, designed for efficient addition and removal of elements from both ends, offers an optimized solution for list rotation. Its built-in rotate() method simplifies this operation.

By converting the original list to a deque, we can utilize the rotate() method to perform efficient rotations. For example:

from collections import deque
l = deque([1, 2, 3, 4])
l.rotate(1)  # rotate one position to the right
print(l)  # deque([2, 3, 4, 1])

Additionally, the rotate() method can be called with a negative value to shift elements to the left:

l.rotate(-1)  # rotate one position to the left
print(l)  # deque([1, 2, 3, 4])

Using collections.deque provides a straightforward and efficient mechanism for rotating lists in Python.

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