Data structure problem related to items filtering

Question

I have this data:

There are three columns r_code, wtg_code and rr. Every row can be treated as a collection of object properties. We have to select n number of rows from the existing rows. Considering the row are sorted in decreasing order of r_code, constraints are,

1. Select the rows in decreasing order of r_code, many rows can have the same r_code.
2. If many rows have the same r_code, then select on the basis of decreasing wtg_code.
3. If multiple rows have the same wtg_code then select on the basis of lowest rr.

If you can give the solution in Javascript then it will be better otherwise I welcome any language.

Answer 1

In JavaScript, the data can be represented like this:

let data = [
    { r_code: 5, wtg_code: 8, rr: 3.4 },
    { r_code: 5, wtg_code: 8, rr: 3.4 },
    { r_code: 5, wtg_code: 7, rr: 4.5 },
    { r_code: 4, wtg_code: 6, rr: 1.2 },
    { r_code: 4, wtg_code: 6, rr: 2.4 },
    { r_code: 4, wtg_code: 6, rr: 4.5 },
    { r_code: 2, wtg_code: 6, rr: 1.6 },
    { r_code: 2, wtg_code: 5, rr: 7.4 },
    { r_code: 1, wtg_code: 4, rr: 3.1 },
    { r_code: 1, wtg_code: 4, rr: 2.9 },
    { r_code: 1, wtg_code: 3, rr: 3.3 },
];

Considering the row are sorted in decreasing order of r_code

That could still allow for several permutations. The rules for selection really mean that you should sort the data more precisely: by descending r_code, descending wtg_code and ascending wtg_code.

For that you can use the sort method.

data.sort((a, b) => b.r_code - a.r_code || b.wtg_code - a.wtg_code || a.rr - b.rr);

Finally, if you are interested in the first 10 (n=10), then slice:

let n = 10;
console.log(data.slice(0, n));