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up vote -5 down vote favorite
1

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)

share|improve this question
    
See developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… – Oldskool Aug 11 '15 at 7:58
10  
I am tempted to write array.map(Math.max.apply.bind(Math.max, null)) as answer. – thefourtheye Aug 11 '15 at 7:58
    
@thefourtheye it works perfectly! Put it as answer, I upvote you: jsfiddle.net/3qf9qxu2 – Marcos Pérez Gude Aug 11 '15 at 8:00
3  
@thefourtheye: That's just awful. Beautiful. Awful. Beautiful. Aaaaah! – T.J. Crowder Aug 11 '15 at 8:00
1  
@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 8:02
up vote 1 down vote

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;
}
share|improve this answer
up vote 0 down vote

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

share|improve this answer
up vote 0 down vote

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]]);
share|improve this answer

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