Divide a list in the following manner

Question

I have this list

list=[0,1,2,3,4,2,6]

I want to make another list of tuples like this:

list=[(0,1),(1,2),(2,3),(3,4),(4,2),(2,6)]

Is there a built-in function that i can use?

use [zip](https://docs.python.org/3/library/functions.html#zip) — Dani Mesejo, Dec 28 '18 at 00:38
Do not use list as a variable name, it shadows the built-int [list](https://docs.python.org/3/library/stdtypes.html#list) function — Dani Mesejo, Dec 28 '18 at 00:41

Sheldore · Accepted Answer · 2018-12-28T00:59:24.937

2

You can use zip and list comprehension. listt[1:] starts from the second element. This is done because in your first pair, you have the 1st and the 2nd element. zip creates pairs and then you iterate over them and use () to store them as tuples.

A piece of advice: Do not use builtin names as variables. list in your case.

listt=[0,1,2,3,4,2,6]

result = [(i) for i in zip(listt, listt[1:])]
# [(0, 1), (1, 2), (2, 3), (3, 4), (4, 2), (2, 6)]

Benchmarking performance

Based on @prashant rana's comment, I compared the performance of zip with his approach taking a list 1 million times longer than the original list. Below are the results: zip turns out to be faster

import timeit
listt=[0,1,2,3,4,2,6]*1000000

%timeit [(listt[i],listt[i+1]) for i in range(len(listt)-1)]
%timeit [(i) for i in zip(listt, listt[1:])]

1.76 s ± 178 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
937 ms ± 46.6 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)

edited Dec 28 '18 at 00:59

answered Dec 28 '18 at 00:39

Sheldore

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using zip will make it slow . – sahasrara62 Dec 28 '18 at 00:43
Might be true but I am assuming the OP is not using it for production purposes. For small lists, like in the question, it serves the purpose – Sheldore Dec 28 '18 at 00:44
i find it's execution time twice the execution time of mine – sahasrara62 Dec 28 '18 at 00:53
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@prashantrana: Check my edit for a list 1 million times larger than the original list. `zip` is faster than your method – Sheldore Dec 28 '18 at 01:00
yes `zip` really is more faster. – sahasrara62 Dec 28 '18 at 01:16

score 0 · Answer 2 · answered Dec 28 '18 at 00:40

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[(i, list[idx + 1]) for idx, i in enumerate(list) if idx < len(list) - 1]

[(0, 1), (1, 2), (2, 3), (3, 4), (4, 2), (2, 6)]

answered Dec 28 '18 at 00:40

ic3b3rg

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score 0 · Answer 3 · edited Dec 28 '18 at 00:55

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There's no builtin function, but python makes it very easy to make your own. Here you go:

list = [0, 1, 2, 3, 4, 2, 6]
x = [(list[i], list[i+1]) for i in range(len(list)-1)]

edited Dec 28 '18 at 00:55

Eb946207

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answered Dec 28 '18 at 00:40

JimmyCarlos

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Divide a list in the following manner

3 Answers3