Get multiple highest values from array of objects

Question

I've got an array of objects:

[
  {
    questionId: 1,
    delta: 3,
  },
  {
    questionId: 3,
    delta: 11,
  },
  {
    questionId: 6,
    delta: 11,
  }
  ....
]

With up to 43 entries.

To get the entry with the highest delta out of this, I would do something like

const maxDelta = Math.max.apply(Math, array.map(question=> {
    return question.delta;
}));

But now I need the 10 highest delta's out of this array. How would I do that?

i'd say use a loop that breaks when no elements are left or 10 is reached , each time you find a value store it and delete it from the array and go again — Alaa Eddine Cherif
– Alaa Eddine Cherif, Commented Aug 1, 2022 at 14:42
Please visit help center, take tour to see what and How to Ask. Do some research, search for related topics on SO; if you get stuck, post a minimal reproducible example of your attempt, noting input and expected output, preferably in a Stacksnippet — mplungjan
– mplungjan, Commented Aug 1, 2022 at 14:42
Since the size of the array is tiny, just sort it with a custom comparator and then take the first ten. — trincot
– trincot, Commented Aug 1, 2022 at 14:44

trincot · Accepted Answer · 2022-08-01 14:51:25Z

1

If the array were huge you'd probably look into a heap or selection-based algorithm, but as your array is tiny (with up to 43 elements), you can just sort it in descending order of delta:

const array = [{questionId: 1,delta: 3,},{questionId: 3,delta: 11,},{questionId: 6,delta: 11,},{questionId: 7,delta: 8,},{questionId: 8,delta: 6,},{questionId: 10,delta: 4,},{questionId: 12,delta: 7,},{questionId: 13,delta: 16,},{questionId: 16,delta: 2,},{questionId: 17,delta: 14,},{questionId: 18,delta: 12,},{questionId: 21,delta: 19,},{questionId: 23,delta: 5,}];
const result = array.sort((a, b) => b.delta - a.delta)
                    .slice(0, 10)
                    .map(a => a.delta);
console.log(result);

answered Aug 1, 2022 at 14:51

trincot

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Comments

nem0z · Accepted Answer · 2022-08-01 14:48:52Z

1

Instead of get max value, you can sort by value then slice the array to get the top 10

First line juste populate te array with random data for exemple :

const getRandomInt = max => Math.floor(Math.random() * max);

const entries = Array(50).fill({})
    .map((x, i) => ({questionId: i, delta: getRandomInt(15)}));

const top10 = entries.sort((a, b) => b.delta - a.delta).slice(0, 10);
console.log(top10);

answered Aug 1, 2022 at 14:48

nem0z

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