best way to flatten n-level array into 2d array

Question

I know there are a lot of ways to flatten an array in javascript, but I want to know what's the best way to flatten an n-level array into a 2D array

Input array looks like this : [[[[1,2]]],[2,3]] i need to convert this into [[1,2],[2,3]]

I tried using array.flat() but it flattens only 1 step and I also tried array.flat(Infinity) but it flattens the whole array into 1D array

the problem is am not sure how deeply nested my input array is. I could think of iterating recursively but am looking if js has any optimised&ready-made way of achieving this?

Have you tried lodash methods?

Pasan Sumanaratne
– Pasan Sumanaratne

2021-05-07 10:58:25 +00:00
Commented May 7, 2021 at 10:58 — Pasan Sumanaratne
– Pasan Sumanaratne, Commented May 7, 2021 at 10:58
can you suggest which one to use ?

aravind_reddy
– aravind_reddy

2021-05-07 11:12:17 +00:00
Commented May 7, 2021 at 11:12 — aravind_reddy
– aravind_reddy, Commented May 7, 2021 at 11:12

Nenad Vracar · Accepted Answer · 2021-05-07 10:58:50Z

2

You could combine map and flat(Infinity) methods to flatten each sub-array to 1D.

const flatDeep = data => data.map(e => e.flat(Infinity))
console.log(flatDeep([[[[1,2]]],[2,3]]))
console.log(flatDeep([[[[1,2]]],[2,[[[3, [4]]]]]]))

answered May 7, 2021 at 10:58

Nenad Vracar

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5 Comments

aravind_reddy Over a year ago

This looks good but it doesn't keep the last level of grouping intact.. i want [[[[1,2],[3,4]]],[2,3]] to be converted to [[1,2],[2,3],[2,3]] not [[1,2,3,4],[2,3]]

Nenad Vracar Over a year ago

@aravind_reddy So what should be the result in this case [[[[1,2]]],[2,[[[3, [4]]]]]]?

aravind_reddy Over a year ago

it should be [[1,2],[2,3,4]] i guess

Nenad Vracar Over a year ago

@aravind_reddy So what is the logic there?

aravind_reddy Over a year ago

sorry i think what you gave is good I will post the other requirements in another question altogether

Rahul Kumar · Accepted Answer · 2021-05-07 11:02:45Z

0

Iterate the array and then use Array.flat(Infinity) method.

const list = [[[[1,2]]],[2,3],[[3,4]]]
const result = [];
for (value of list) {
  result.push(value.flat(Infinity));
}
console.log(result);

answered May 7, 2021 at 11:02

Rahul Kumar

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