How to Rotate a Python List Right or Left by Specified Positions?

Shifting Lists in Python: Rotation Right and Left

Question:

How can you rotate a Python list by a specified number of positions, either to the right or left?

Answer:

The following function accomplishes this task:

<code class="python">def rotate(l, n):
    return l[-n:] + l[:-n]</code>

Explanation:

• l[-n:] creates a new list containing the last n elements from the right end of the original list.
• l[:-n] creates a new list containing the remaining elements from the original list.
• Concatenating these two lists ([l[-n:]] [l[:-n]]) effectively shifts the list by n positions to the right.

Alternative Implementation:

For a more conventional rightward shift, use this function:

<code class="python">def rotate(l, n):
    return l[n:] + l[:n]</code>

Example:

Consider the example list [1, 2, 3, 4, 5].

<code class="python">rotate([1, 2, 3, 4, 5], 2)
# [3, 4, 5, 1, 2]</code>

Additional Notes:

• The rotate function returns a new list and does not modify the input list.
• The argument n can be negative to rotate the list to the left.

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