how to return the largest number from each sub array using javascript?

Question

How do I return the largest numbers from each sub array of a multidimension array? the output will be an array of largest numbers.

For example array = [[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]

returning value [ 5, 27, 39, 1001 ]

I tried like

function largestOfFour(arr) {

  for(var i = 0; i < arr.length; i++) {
    large = 0;
    for(var j = 0; j < arr[i].length; j++) {
      if(arr[i][j] > large) {
        large = arr[i][j];
      }
    }
  }
  return arr.push(large);
}

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);

the output is only largest of first sub array (5)

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/max — Oldskool, Aug 11 '15 at 07:58
I am tempted to write `array.map(Math.max.apply.bind(Math.max, null))` as answer. — thefourtheye, Aug 11 '15 at 07:58
@thefourtheye it works perfectly! Put it as answer, I upvote you: http://jsfiddle.net/3qf9qxu2/ — Marcos Pérez Gude, Aug 11 '15 at 08:00
@thefourtheye: That's just awful. Beautiful. Awful. Beautiful. Aaaaah! — T.J. Crowder, Aug 11 '15 at 08:00
@T.J.Crowder I know :D If OP had made some effort I would have added that also in the answer and explained it :( — thefourtheye, Aug 11 '15 at 08:02
Please check this out and then restructure your question: http://stackoverflow.com/help/how-to-ask — hlh3406, Aug 11 '15 at 08:09
It would be also better to transfer this question to Community wiki — hindmost, Aug 11 '15 at 08:13
@hindmost I have tried this function largestOfFour(arr) { for(var i = 0; i < arr.length; i++) { large = 0; for(var j = 0; j < arr[i].length; j++) { if(arr[i][j] > large) { large = arr[i][j]; } } } return arr.push(large); } largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]); — J. Sadana, Aug 11 '15 at 09:19
@thefourtheye thank you. but it can done by using for loop and if statement? — J. Sadana, Aug 11 '15 at 09:31

score 2 · Answer 1 · answered Jul 15 '16 at 15:07

I have been through the code and ended with a final solution. The first for loop iterates through the big array and the second one through the components of the subarray. The if checks for the biggest number.

function largestOfFour(arr) {
  var main = [];
  for(k=0;k<arr.length;k++){
     var long=0;
       for(i=0;i<arr[k].length;i++){
          if(long<arr[k][i]) {
              long=arr[k][i];
          }
       }
   main.push(long);
   }
  return main;
}

score 1 · Answer 2 · answered Aug 23 '15 at 08:48

i have got answer to my question

function largestOfFour(arr) {
  var newArr = [];
  for (i=0; i<arr.length; i++) {
    var largest = 0;
    for (j=0; j<arr[i].length; j++) {
      if (arr[i][j] > largest) {
        largest = arr[i][j];
      }
    }
    newArr.push(largest);
  }
  // You can do this!
  return newArr;
}

largestOfFour([[4, 5, 1, 3], [13, 27, 18, 26], [32, 35, 37, 39], [1000, 1001, 857, 1]]);

score 0 · Answer 3 · answered Aug 11 '15 at 11:21

0

If you want to use a simple loop, you need to create a return array and push the results there. In your code you have pushed an item only at the end (return arr.push(large)).

Hope it's clear

Regards,

Dan

answered Aug 11 '15 at 11:21

Daniel Rosano

695
5
16

how to return the largest number from each sub array using javascript?

3 Answers3

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