How to create an array from two others that will contain common pairs (sequences) of numbers?

Question

a = [1,2,3,4,5,6,8]
b = [6,8,9,4,5,3,2,1]

final result should be

c = [6,8,4,5]

This array contains the same pair of numbers in both arrays - how to write this kind of code in python?

I only known how to create an array with duplicated values

a = [1,2,3,4,5,6,8]
b = [6,8,9,4,5,3,2,1]
c = [x for x in a if x in b]
print (c)

Possible duplicate of [How to find list intersection?](https://stackoverflow.com/questions/3697432/how-to-find-list-intersection) — RoadRunner, Jul 18 '18 at 10:23
I think you want to check 2(pair) item at a time in second list right? — Chetan Ameta, Jul 18 '18 at 10:30
final array should contains duplicated pair/pairs of number that are next to each other - so in that case only pairs - (4,5) and (6,8) match this condition - cause both are in two arrays - a and b — Łukas Ptak, Jul 18 '18 at 10:39
@ŁukasPtak Next time try to be that clear when first asking your question, it might have saved it being put on hold as unclear :) — Nick is tired, Jul 18 '18 at 10:42
@NickA: because both lists contain the 2-tuples `4,5` and `6,8` — AcK, Jul 18 '18 at 10:42

score 5 · Answer 1 · answered Jul 18 '18 at 10:33

5

>>> [e for t in [t for t in zip(b,b[1:]) if t in zip(a,a[1:])] for e in t]
[6, 8, 4, 5]

answered Jul 18 '18 at 10:33

Sunitha

This is great! Very elegant. – Ashish Acharya Jul 18 '18 at 10:35
1

How did you even figure out what OP was trying to do – Nick is tired Jul 18 '18 at 10:35
2

@NickA. OP has mentioned `duplicated pairs of numbers` in the title :) – Sunitha Jul 18 '18 at 10:37
1

@Sunitha That is one of the most obscurely asked questions I've seen on SO >. – Nick is tired Jul 18 '18 at 10:38
I commend you for figuring out what the OP wanted. I was clueless. – RoadRunner Jul 18 '18 at 10:39
quick and elegant. – Chetan Ameta Jul 18 '18 at 10:40
@NickA. I have to agree on that.. Even I had to think for a while to figure what OP was asking – Sunitha Jul 18 '18 at 10:41
sorry for causing such a problem. But yes - final array should contains duplicated pair/pairs of numbers that are next to each other - so in that case only pairs (6,8) and (4,5) fulfill this condition – Łukas Ptak Jul 18 '18 at 10:43

1 Answers1