Slicing by an increment of -2 not working

Question

In the case of this function starting from -2 position, it should print [115,43].

def increment(nums):


    t = (nums[-2:-4:-2 ])
    print(t)

    print(increment([43, 90, 115, 500]))

However, the output for this code is just [115], how come?

Remember, Python ranges are exclusive of the second bound. To get the behavior you indicated, replace -4 with -5. — Tom Karzes, Aug 20 '22 at 05:19
Does this answer your question? [Why does range(start, end) not include end?](https://stackoverflow.com/questions/4504662/why-does-rangestart-end-not-include-end) — Gino Mempin, Aug 20 '22 at 05:20

score 0 · Answer 1 · answered Aug 20 '22 at 05:26

0

If you use [-2:-4:-1], you can see that the result is [115, 90] and 43 is not included. That's because python ranges are exclusive of the second bound.

If you want to include 43, you should use [-2:-5:-2]. Then the result would be [115, 43]

answered Aug 20 '22 at 05:26

Amin

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score 0 · Answer 2 · answered Aug 20 '22 at 05:40

Try this code,

def increment(nums):
    print(nums[-2:-5:-2]) # output: [115, 43]

increment([43, 90, 115, 500])

slicing in python: slice(start, end, step)

when you give nums[-2:-4:-2 ] python will start from 115 and jumps 2 positions to the left and reach at 43 but you have set the end as 90 (-4 will go upto -3 position, not 43)

So, I just changed the end index to -5

Slicing by an increment of -2 not working

2 Answers2