get highest element in a two dimensional array

Question

i have this array:

const myArray = [["Cow", 3], ["Pig", 5], ["Pig", 10], ["Pig", 4], ["Chicken", 1], ["Cow", 1], ["Cow" , 12], ["Cow", 11], ["Chicken", 12]]

and want to turn into this: (only the highest of each one)

[ [ 'Pig', 10 ], [ 'Cow', 12 ], [ 'Chicken', 12 ] ]

but with my code i cant get the last one, i cant find why tho

const myArray = [["Cow", 3], ["Pig", 5], ["Pig", 10], ["Pig", 4], ["Chicken", 1], ["Cow", 1], ["Cow" , 12], ["Cow", 11], ["Chicken", 12]]

function getHighest() {

  var onlyHighest = [];

  myArray.sort(
    function(a,b) {
      if (a[0] == b[0])
       return a[1] < b[1] ? -1 : 1;
      return a[0] < b[0] ? 1 : -1;
    }
  );  

  myArray.forEach((a, i) => {
    var i = i+1;
    if (i < myArray.length) {
      if (a[0] != myArray[i][0]){
        onlyHighest.push([a[0], a[1]]);
      }
    }
  });

  return console.log(onlyHighest)
  //    [ [ 'Pig', 10 ], [ 'Cow', 12 ] ]
}

Answer 1

Use an object to hold the current highest value for each animal. Loop through the array, replacing the value when it's higher than the value in the object.

 const myArray = [["Cow", 3], ["Pig", 5], ["Pig", 10], ["Pig", 4], ["Chicken", 1], ["Cow", 1], ["Cow" , 12], ["Cow", 11], ["Chicken", 12]] function getHighest(array) { let obj = {}; array.forEach(([key, value]) => { if (key in obj) { if (value > obj[key]) { obj[key] = value; } } else { obj[key] = value; } }); return Object.entries(obj); } console.log(getHighest(myArray));

Answer 2

Your

myArray.forEach((a, i) => {
  var i = i+1;
  if (i < myArray.length) {

is causing the problem and is pretty confusing. If the last sorted chunk of the array contains only 2 elements, that condition won't be fulfilled, so nothing from that chunk will be pushed.

A quick fix would be to unconditionally push the original element if it's the last one in the array.

myArray.forEach((a, i) => {
  if (i === myArray.length - 1) {

A better refactor would be to group the input into an object that keeps the largest value for each property, no sorting involved.

 const myArray = [["Cow", 3], ["Pig", 5], ["Pig", 10], ["Pig", 4], ["Chicken", 1], ["Cow", 1], ["Cow" , 12], ["Cow", 11], ["Chicken", 12]] const grouped = {}; for (const [prop, num] of myArray) { grouped[prop] = Math.max(num, grouped[prop] ?? -Infinity); } const onlyHighest = Object.entries(grouped); console.log(onlyHighest);

Answer 3

How about a simple sort

function funk() {
  let a = [["Cow", 3], ["Pig", 5], ["Pig", 10], ["Pig", 4], ["Chicken", 1], ["Cow", 1], ["Cow", 12], ["Cow", 11], ["Chicken", 12]];
  let r = a.sort((a, b) => {
    return b[1] - a[1]
  })[0];
  Logger.log(r);
}

Execution log
12:37:11 PM Notice  Execution started
12:37:11 PM Info    [Cow, 12.0]
12:37:12 PM Notice  Execution completed