How to create an array of sorted indexes of another array in typescript?

Question

I am trying to get an ordered array of index from another array in typescript.

Let me give examples: consider a function that receives an array of any size and returns another array with the ordered indexes of the Input:

ex1: Input=(5.3, 2.4, 4.5, 6.2) > Output=(1,2,0,3).
ex2: Input=(10, 11, 5, 34, 3, 7, 17) > Output=(4,2,5,0,1,6,3).

I can't use array.sort() as will change the original array.

I'm stuck, as I have very litle experience whit JS and TS (rusty Delphi programmer).

Thanks in advance for any thoughts.

charlietfl · Accepted Answer · 2020-11-29 01:50:31Z

1

Use slice() to make a copy you can sort without mutating original, then map() to create an array of each sorted element's index in the original array.

const data = [5.3, 2.4, 4.5, 6.2],
      data2 = [10, 11, 5, 34, 3, 7, 17];

const sortedIndex = (arr) => {
  return arr.slice().sort((a, b) => a - b).map(n => arr.indexOf(n))
}

console.log(JSON.stringify(sortedIndex(data)));
console.log(JSON.stringify(sortedIndex(data2)));

edited Nov 29, 2020 at 1:50

answered Nov 29, 2020 at 1:43

charlietfl

172k14 gold badges125 silver badges154 bronze badges

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

1 Comment

Serginho Over a year ago

Perfect! Thank you.

Penguin · Accepted Answer · 2020-11-29 01:28:51Z

0

Can you just copy the array then sort the copy?

var array0 = [4,2,5,7,1.6];
var array1 = [];
for(var i=0;i<array0.length;i++){
  array1.push(array0[i]);
}
array1.sort();
//array0 = [4,2,5,6,1.6]
//array1 = [1.6,2,4,5,6]

edited Nov 29, 2020 at 1:28

answered Nov 29, 2020 at 1:27

Penguin

4414 silver badges17 bronze badges

4 Comments

charlietfl Over a year ago

This does not make a copy. Try running this yourself. The variables are both references to same array

charlietfl Over a year ago

Only if values are less than 10. Default for sort is to convert to string and 11 would come before 2

Serginho Over a year ago

Thanks. i think in that case i would get the input array sorted, but not the indexes from the input array sorted into a new array! for this ex.of the array0 I would like to get: output = (4,1,0,2,3)! The array i am using is only numbers!

Penguin Over a year ago

My bad, I thought they just wanted to use the .sort() method and not have it modify the original array, just misinterpreted the question

emonz · Accepted Answer · 2020-11-29 01:49:04Z

0

Only need two lines of code to do this:

var unsortedArray = [6, 4, 9, 1, 5];
var sortedArray = unsortedArray.slice().sort();

console.log(sortedArray);      // [1, 4, 5, 6, 9]
console.log(unsortedArray);    // [6, 4, 9, 1, 5]

edited Nov 29, 2020 at 1:49

answered Nov 29, 2020 at 1:43

emonz

4,7441 gold badge12 silver badges4 bronze badges

Collectives™ on Stack Overflow

How to create an array of sorted indexes of another array in typescript?

3 Answers 3

1 Comment

4 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related