get highest element in a two dimensional array

June 2, 2022

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 ] ]
}

>Solution :

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));