Sort 2D array of pairs in JavaScript

Question

I need to sort 2D array of pairs in JavaScript.

const a = [
  [1, 1],
  [1, 2],
  [1, 3],
  [5, 6]
]
const b = [
  [5, 6],
  [1, 2],
  [1, 3],
  [1, 1]
]
b.sort((c, d) => d[0] + d[1] - c[0] + c[1]);
console.log(b)

function compare(a, b) {
  if (a.length != b.length) return false;
  for (let i = 0; i < b.length; i++)
    for (let j = 0; j < b[i].length; j++)
      if (a[i][j] !== b[i][j]) return false;
  return true;
}
console.log(compare(a, b))

I want to sort array b to be equal to array a. Of course real life array is much longer. This is just an example.

I have written function for comparing, but sort function doesn't work properly. Could you please help me to fix this?

Michael M. · Accepted Answer · 2023-01-11 03:01:49Z

1

First, d[0] + d[1] - c[0] + c[1] is backwards. You should subtract the elements of d from c, not the other way around. Like this: c[0] + c[1] - d[0] + d[1].

Second, you have an order of operations error. You need to subtract the elements of d from c, but your current code subtracts one element of d and adds the other. You need to distribute the negative sign, just like this: c[0] + c[1] - d[0] - d[1]

const a = [
  [1, 1],
  [1, 2],
  [1, 3],
  [5, 6]
]
const b = [
  [5, 6],
  [1, 2],
  [1, 3],
  [1, 1]
]
b.sort((c, d) => c[0] + c[1] - d[0] - d[1]);
console.log(b)

function compare(a, b) {
  if (a.length != b.length) return false;
  for (let i = 0; i < b.length; i++)
    for (let j = 0; j < b[i].length; j++)
      if (a[i][j] !== b[i][j]) return false;
  return true;
}
console.log(compare(a, b))

edited Jan 11, 2023 at 3:01

answered Jan 11, 2023 at 2:23

Michael M.

11.2k11 gold badges22 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

10 Comments

codproe Over a year ago

thank you very much, I have another question. How could I remove duplicates from this array? Do you have any idea? It would help me a lot

Michael M. Over a year ago

A simple way would be to convert it to a Set then back to an Array. Just like this: let newArray = [...new Set(oldArray)]

codproe Over a year ago

I tried it but it doesn't work with this type of 2D array, it works with 1D array

Michael M. Over a year ago

@codproe Ah yes, sorry. In that case, I'd just loop over every subarray of the 2d array. Like this: let newTwoD = oldTwoD.map(arr => [...new Set(arr)])

codproe Over a year ago

I tried this array [5, 6], [1, 2], [1, 3], [1, 1], [1,1] and result was [5, 6], [1, 2], [1, 3], [1], [1]

|

Collectives™ on Stack Overflow

Sort 2D array of pairs in JavaScript

1 Answer 1

10 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

10 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related