Randomising array from a matrix (bidimensional array)

Question

I Currently have the following matrix

const fileName = [
  ["a01", "b01", "c01", "d01", "e01", "f01", "g01", "h01", "i01", "j01", "k01", "l01"],
  ["a02", "b02", "c02", "d02", "e02", "f02", "g02", "h02", "i02", "j02", "k02", "l02"],
  ["a03", "b03", "c03", "d03", "e03", "f03", "g03", "h03", "i03", "j03", "k03", "l03"],
  ["a04", "b04", "c04", "d04", "e04", "f04", "g04", "h04", "i04", "j04", "k04", "l04"],
  ["a05", "b05", "c05", "d05", "e05", "f05", "g05", "h05", "i05", "j05", "k05", "l05"],
  ["a06", "b06", "c06", "d06", "e06", "f06", "g06", "h06", "i06", "j06", "k06", "l06"],
  ["a07", "b07", "c07", "d07", "e07", "f07", "g07", "h07", "i07", "j07", "k07", "l07"],
  ["a08", "b08", "c08", "d08", "e08", "f08", "g08", "h08", "i08", "j08", "k08", "l08"],
  ["a09", "b09", "c09", "d09", "e09", "f09", "g09", "h09", "i09", "j09", "k09", "l09"],
  ["a10", "b10", "c10", "d10", "e10", "f10", "g10", "h10", "i10", "j10", "k10", "l10"],
  ["a11", "b11", "c11", "d11", "e11", "f11", "g11", "h11", "i11", "j11", "k11", "l11"],
  ["a12", "b12", "c12", "d12", "e12", "f12", "g12", "h12", "i12", "j12", "k12", "l12"]
];

and I create a new array with filenames from it randomising 1 item of each subarray using this function:

function randomise() {
  let sequence = fileName.map(option => {
    const random = Math.floor(Math.random() * 11);
    return option[random];
  });
  let randomSelection = sequence.map(createURL);
  function createURL(fileName) {
    return `assets/music/${fileName}.mp3`;
  }
  console.log(randomSelection);
}

So I get an array such as:

["assets/music/f01.mp3", "assets/music/f02.mp3", "assets/music/b03.mp3", "assets/music/k04.mp3", "assets/music/b05.mp3", "assets/music/f06.mp3", "assets/music/i07.mp3", "assets/music/d08.mp3", "assets/music/d09.mp3", "assets/music/g10.mp3", "assets/music/a11.mp3", "assets/music/d12.mp3"]

But I want to rearrange my matrix in this way:

const fileName = [
  ["a01", "a02", "a03", "a04", "a05", "a06", "a07", "a08", "a09", "a10", "a11", "a12"],
  ["b01", "b02", "b03", "b04", "b05", "b06", "b07", "b08", "b09", "b10", "b11", "b12"],
  ["c01", "c02", "c03", "c04", "c05", "c06", "c07", "c08", "c09", "c10", "c11", "c12"],
  ["d01", "d02", "d03", "d04", "d05", "d06", "d07", "d08", "d09", "d10", "d11", "d12"],
  ["e01", "e02", "e03", "e04", "e05", "e06", "e07", "e08", "e09", "e10", "e11", "e12"],
  ["f01", "f02", "f03", "f04", "f05", "f06", "f07", "f08", "f09", "f10", "f11", "f12"],
  ["g01", "g02", "g03", "g04", "g05", "g06", "g07", "g08", "g09", "g10", "g11", "g12"],
  ["h01", "h02", "h03", "h04", "h05", "h06", "h07", "h08", "h09", "h10", "h11", "h12"],
  ["i01", "i02", "i03", "i04", "i05", "i06", "i07", "i08", "i09", "i10", "i11", "i12"],
  ["j01", "j02", "j03", "j04", "j05", "j06", "j07", "j08", "j09", "j10", "j11", "j12"],
  ["k01", "k02", "k03", "k04", "k05", "k06", "k07", "k08", "k09", "k10", "k11", "k12"]
];

I need to randomly select 1 item from each of the indexes of those subarrays, so one random item ending with "1", another ending with "2", etc Could you help me please? Thanks!

Answer 1

If these are the actual values of the array you're using, you can just loop from 1 through 12 and stick it together with a random character from the string "abcdefghijk" using randojs' rando() function (or otherwise if you prefer).

for(var i = 1; i <= 12; i++){
  console.log("assets/music/" + rando("abcdefghijk") + (i < 10 ? "0" : "") + i + ".mp3")
}

<script src="https://randojs.com/1.0.0.js"></script>

This code uses randojs.com to simplify the randomness and make it easier to read, so if you want to use this code, make sure this is in the head tag of your html document:

<script src="https://randojs.com/1.0.0.js"></script>

---

To answer the second part of your question (which you posted as another answer to this question), you don't need to keep your fileName variable to construct the HTML here if you'd rather not. You can do it like this instead:

var letters = "abcdefghijk";
for(var i = 0; i < letters.length; i++){
    var musicRowID = letters.charAt(i) + "01";
    $("#music-grid").append(`<div id="music-row-${musicRowID}" class="row no-gutters"></div>`);

    for(var j = 1; j <= 12; j++){
        var columnID = letters.charAt(i) + (j < 10 ? "0" : "") + j;
        $(`#music-row-${musicRowID}`).append(`<div class="col-1"><button id="${columnID}" class="btn bar song">${columnID.toUpperCase()}</button></div>`);
    }
}

Answer 2

Very beautiful Aaron! I created the array like this:

let randomSelection = new Array();

function randomise() {
  for (let i = 1; i <= 12; i++) {
    let index = `assets/music/${rando("abcdefghijkl")}${i < 10 ? "0" : ""}${i}.mp3`;
    randomSelection.push(index);
  }
}

randomise()

The only problem now is that I was using the code below to populate a grid based in my fileName variable...

fileName.forEach(row => {
  $("#music-grid").append(`<div id="music-row-${row.slice(0, 1)}" class="row no-gutters"></div>`);
  row.forEach(col => {
    $(`#music-row-${row.slice(0, 1)}`).append(
      `<div class="col-1"><button id="${col}" class="btn bar song">${col.toUpperCase()}</button></div>`
    );
  });
});

Do you reckon it is better to keep my original fileName variable in order to allow it to populate the grid?

Thanks so much!

Answer 3

If I understood you correctly this will give you your desired output. Picking one letter for each number. Hope this helps for whatever you need it.

const fileName = [
  ["a01", "a02", "a03", "a04", "a05", "a06", "a07", "a08", "a09", "a10", "a11", "a12"],
  ["b01", "b02", "b03", "b04", "b05", "b06", "b07", "b08", "b09", "b10", "b11", "b12"],
  ["c01", "c02", "c03", "c04", "c05", "c06", "c07", "c08", "c09", "c10", "c11", "c12"],
  ["d01", "d02", "d03", "d04", "d05", "d06", "d07", "d08", "d09", "d10", "d11", "d12"],
  ["e01", "e02", "e03", "e04", "e05", "e06", "e07", "e08", "e09", "e10", "e11", "e12"],
  ["f01", "f02", "f03", "f04", "f05", "f06", "f07", "f08", "f09", "f10", "f11", "f12"],
  ["g01", "g02", "g03", "g04", "g05", "g06", "g07", "g08", "g09", "g10", "g11", "g12"],
  ["h01", "h02", "h03", "h04", "h05", "h06", "h07", "h08", "h09", "h10", "h11", "h12"],
  ["i01", "i02", "i03", "i04", "i05", "i06", "i07", "i08", "i09", "i10", "i11", "i12"],
  ["j01", "j02", "j03", "j04", "j05", "j06", "j07", "j08", "j09", "j10", "j11", "j12"],
  ["k01", "k02", "k03", "k04", "k05", "k06", "k07", "k08", "k09", "k10", "k11", "k12"]
];

let pickedValues = [];

for (i = 0; i <= fileName.length; i++) {
  let index = Math.floor(Math.random() * ((fileName.length - 1) - 0 + 1));
  pickedValues[i] = (fileName[index][i]);
}
console.log(pickedValues);