Tricks of List Slicing in Python
Python slicing is a computationally fast way to methodically access parts of your data. The colons (:) in subscript notation make slice notation - which has the optional arguments, start, stop, step.
Various slicing tricks
items = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] print(items[4:]) # From index 4 to last index print(items[:4]) # From index 0 to 4 index print(items[4:7]) # From index 4(included) up to index 7(excluded) print(items[:-1]) # Excluded last item print(items[:-2]) # Up to second last index(negative index) print(items[::-1]) # From last to first in reverse order(negative step) print(items[::-2]) # All odd numbers in reversed order print(items[-2::-2]) # All even numbers in reversed order print(items[::]) # All items
Output
[4, 5, 6, 7, 8, 9] [0, 1, 2, 3] [4, 5, 6] [0, 1, 2, 3, 4, 5, 6, 7, 8] [0, 1, 2, 3, 4, 5, 6, 7] [9, 8, 7, 6, 5, 4, 3, 2, 1, 0] [9, 7, 5, 3, 1] [8, 6, 4, 2, 0] [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]