Get array key of subarray with the greatest value

Question

I have an array in javascript with this structure:

controllers: Array(2)
    0: Object
        vram: 4095
    1: Object
        vram: 1024

This array is generated via si.graphics. There can be more sub-arrays with different values.

I need to somehow return just the index of the controller with the most vram. I've found other stack questions about something similar, but seemingly only with flat arrays, but this array is multi-dimensional.

I haven't tried much to accomplish this because I simply do not know where to start.

How can I get the index of the sub-array with the most vram?

This is not a duplicate because it is focusing on getting the highest value itself, which is pretty trivial and is not what I am/was asking for.

@Luca I didn't mean that the structure is how the array is made. Just that it is the current structure of the array, I'm simply showing you the values and how it is set up. I'm not asking whether the array is valid. — GrumpyCrouton, May 04 '18 at 18:54
It'd still be best to show the array in a valid format. We can determine the structure of a valid array quite easily. — Cory Kleiser, May 04 '18 at 18:55
So what is the structure then? Could you please add a [mcve] explaining what you tried and what didn't work? — Luca Kiebel, May 04 '18 at 18:55
Arrays dont have keys rather indexes. indexes are their keys however. — Rikin, May 04 '18 at 18:56
@Luca I have done that. It has nothing to do with the structure of the array. I was outlining the values that matter, and showing they are a subarray of an array. — GrumpyCrouton, May 04 '18 at 18:56
@Rikin That's probably just the PHP in my brain mixing up wordings. — GrumpyCrouton, May 04 '18 at 18:56
Give me a second, going to update the post with the structure from `console.log()`. — GrumpyCrouton, May 04 '18 at 18:57
@Rikin Array indices are keys: `Object.keys(['',''])` returns `["0","1"]` — Paul, May 04 '18 at 18:59
Possible duplicate of [Finding the max value of an attribute in an array of objects](https://stackoverflow.com/questions/4020796/finding-the-max-value-of-an-attribute-in-an-array-of-objects) — Luca Kiebel, May 04 '18 at 19:01
depending on the use case, I think that you should maybe think of creating a structure similar to a maxHeap. Im just not sure of the regularity of your use case. — Fallenreaper, May 04 '18 at 19:04
@Fallenreaper I can't really change the structure, it's a part of a nodejs module. — GrumpyCrouton, May 04 '18 at 19:16

score 1 · Answer 1 · answered May 04 '18 at 18:59

1

Use something like below

var controllers = {
    0: {
        vram: 4096
    },
    1: {
        vram: 1024
    },
    2: {
        vram: 1024
    }
};

var max = -999999,
  maxKey = -1;


for(var key in controllers) {
  if(controllers[key]['vram'] > max) {
    max = controllers[key]['vram'];
    maxKey = key;
  }
}

console.log(maxKey);
console.log(max);

answered May 04 '18 at 18:59

Saeed

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I think `the index of the sub-array with the most vram` means He needs maximum `vram` and its key! @Luca – Saeed May 04 '18 at 19:02
That's incorrect @Saeed.Ataee - I just need the index. – GrumpyCrouton May 04 '18 at 19:17
Use just `maxKey`. What is the problem? @GrumpyCrouton – Saeed May 04 '18 at 19:18
No, I was just replying to your comment :) – GrumpyCrouton May 04 '18 at 19:19

Cory Kleiser · Answer 2 · 2018-05-04T19:10:35.400

If you are just trying to get the the highest value then the following function in the code snippet will do what you need:

const myArray = [
  {vram: 100},
  {vram: 200},
  {vram: 150}
]

function getHighestVram(array){
  let highestVram = 0;
  for (i in array){
    if(array[i].vram > highestVram) {
      highestVram = array[i].vram;
    }
  }
  return highestVram;
}
    
const maxVram = getHighestVram(myArray);

console.log(maxVram);

If you want to find the index with the highest vram you can use a similar function. Like this:

const myArray = [
  {vram: 100},
  {vram: 200},
  {vram: 150}
]

function getHighestVram(array){
  let highestVram = 0;
  let highestVramIndex;
  for (i in array){
    if(array[i].vram > highestVram) {
      highestVram = array[i].vram;
      highestVramIndex = i;
    }
  }
  return highestVramIndex;
}
    
const maxVramIndex = getHighestVram(myArray);

console.log(maxVramIndex);

score 1 · Accepted Answer · answered May 04 '18 at 19:09

1

You could reduce the array by checking the value and with the value of the last max value.

var controllers = [{ vram: 4095 }, { vram: 1024 }],
    maxIndex = controllers.reduce(
        (r, { vram }, i, a) => !i || vram > a[r].vram ? i : r,
        undefined
    );

console.log(maxIndex);

answered May 04 '18 at 19:09

Nina Scholz

376,160
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I used this in my project. Thank you. – GrumpyCrouton May 04 '18 at 19:19

colxi · Answer 4 · 2018-05-04T19:23:05.633

1

Simply iterate the controllers Object, and check each vram value, storing always the highest one, would do the trick

let controllers =  [
    {"vram":4095},  // index 0
    {"vram":1024},  // index 1
    {"vram":55555}, // index 2
    {"vram":123}    // index 3...
];

let max = 0;
for(let i in controllers){ 
    if(controllers[i].vram > controllers[max].vram ) max = i
}

console.log(max); // outputs 2

edited May 04 '18 at 19:23

answered May 04 '18 at 19:19

colxi

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This was my original plan, but wanted to know if there was a better/more effecient way. Either way, thank you for the answer! – GrumpyCrouton May 04 '18 at 19:21

Get array key of subarray with the greatest value

4 Answers4