How to fill zero to my multidimensional array in javascript?

Question

I am just learning javascript.I am pretty confused with manipulating multidimensional arrays.

var myarr = [ 
       [ 7, 9, 10 ], 
       [ 6, 9 ], 
       [ 5, 9 ] 
  ]

I want to insert zero like this.What is the smart way to do this in javascript

       [ 
           [ 7, 9, 10 ], 
           [ 6, 9, 0 ], 
           [ 5, 9, 0 ] 
       ]

You want to insert zeros dynamically? How many? A zero per array? — Aer0
– Aer0, Commented Oct 17, 2016 at 12:32
No just insert zero like I mentioned.I am using this array to do matrix calculations — Nane
– Nane, Commented Oct 17, 2016 at 12:34
first find the maximum array length then loop through the array and insert required zeros — Madhawa Priyashantha
– Madhawa Priyashantha, Commented Oct 17, 2016 at 12:35
@Nane: You should always include your efforts in your question. This advice is also aimed at whoever the 3 upvoters are! — musefan
– musefan, Commented Oct 17, 2016 at 12:50

Nina Scholz · Accepted Answer · 2016-10-17 12:36:53Z

2

You could get first the max length of the inner arrays and push zeroes until all inner arrays have the same length.

var myarr = [[7, 9, 10], [6, 9], [5, 9]],
    length = myarr.reduce(function (r, a) { return Math.max(r, a.length); }, 0);

myarr.forEach(function (a) {
    while (a.length < length) {
        a.push(0);
    };
});

console.log(myarr);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Oct 17, 2016 at 12:36

Nina Scholz

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Comments

Thalaivar · Accepted Answer · 2016-10-17 12:38:20Z

0

var myarr = [ 
       [ 7, 9, 10 ], 
       [ 6, 9 ], 
       [ 5, 9 ] 
  ]

for(var i = 0; i < myarr.length; i++) {    
    if(myarr[i].length < myarr.length){
       myarr[i].push(0);
    }
}

console.log(myarr);

edited Oct 17, 2016 at 12:38

answered Oct 17, 2016 at 12:34

Thalaivar

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2 Comments

Nane Over a year ago

Its working just update your answer by replacing num 3 with myarr.length coz that's what i expected

musefan Over a year ago

This solution seems a bit limited, it might work for this input but other input will fail. For example, you are assuming the longest length will match the number of sub-arrays. Also, you assume there will only ever be 1 missing element at most for each sub-array.Try this input to see what I mean: [1, 2, 3], [1], [1, 2], [1, 2]

Pugazh · Accepted Answer · 2016-10-17 12:38:36Z

0

Here is a solution.

var myarr = [
  [7, 9, 10],
  [6, 9],
  [5, 9]
];

var rows = myarr.length;
var cols = 0;

for (var i in myarr) {
  if (myarr[i].length > cols)
    cols = myarr[i].length;
}

for (i = 0; i < rows; i++) {
  for (j = 0; j < cols; j++) {
    if (myarr[i][j] == undefined)
      myarr[i][j] = 0;
  }
}

console.log(myarr);

answered Oct 17, 2016 at 12:38

Pugazh

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Comments

musefan · Accepted Answer · 2016-10-17 12:44:32Z

0

Best way would be first to calculate what the longest sub-array length you have, then you can pad the sub-arrays to make them all up to the same length.

The following includes a function for calculating the longest length, and another for performing the padding:

function getMax(arr) {
  var max = 0;
  for (var i = 0; i < arr.length; i++) {
    if (arr[i].length > max)
      max = arr[i].length;
  }
  return max;
}

function pad(arr, max) {
  for (var i = 0; i < arr.length; i++) {
    for (var j = arr[i].length; j < max; j++)
      arr[i].push(0);
  }
}

var myarr = [
  [7, 9, 10],
  [6, 9],
  [5, 9]
];

pad(myarr, getMax(myarr));

console.log(myarr);

answered Oct 17, 2016 at 12:44

musefan

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Comments

Vanojx1 · Accepted Answer · 2016-10-17 12:50:55Z

0

Seems like you need a square matrix from a 2 dimension array, so try this:

var myarr = [
  [7, 9, 10],
  [6, 9],
  [5, 9, 1, 2, 3, 4, 5, 6, 7] // <--- for example purpose
];

var rows = myarr.length;
var cols = 0;

for(var i = 0; i < myarr.length; i++){
  if(myarr[i].length > cols)
    cols = myarr[i].length;
}

var limit = rows > cols ? rows : cols;
for(var i = 0; i < limit; i++){
  if(myarr[i] == undefined)
    myarr[i] = new Array(limit);
  for(var j = 0; j < limit; j++){
    if(typeof myarr[i][j] == "undefined")
      myarr[i][j] = 0;
  }
}

for(var i = 0; i < limit; i++){
  console.log(JSON.stringify(myarr[i]));
}

answered Oct 17, 2016 at 12:50

Vanojx1

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Comments

nivendha · Accepted Answer · 2016-10-17 12:54:26Z

0

var maxLength=0;
for(var i=0;i<myarr.length;i++){
   if(myarr[i].length>maxLength){
      maxLength=myarr[i].length
  }
}
for(var i=0;i<myarr.length;i++){
    if(myarr[i].length!=maxLength){
    fillZeros(myarr[i])
    }
  }
function fillZeros(child){
    while(child.length!=maxLength)
     {child.push(0);}
}

edited Oct 17, 2016 at 12:54

answered Oct 17, 2016 at 12:41

nivendha

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1 Comment

musefan Over a year ago

I appreciate the efforts for keeping the internet storage footprint down! ...but seriously, not very readable is it..

tjgersho · Accepted Answer · 2017-09-08 22:37:23Z

0

If your array is a numbers only arbitrarily nested filled array, you could use a recursive function like I have here:

function fillArray(array,  val){

  for(var i=0; i<array.length; i++){    
    if(typeof(array[i]) === 'number'){
        array[i] = val;
    }else{
        fillArray(array[i],  val);
    }
  } 

}
var test = [5,[3,8,-1,[3,4,5,2,1],[2] ],[[2,2],[3]],[[2,3],[4]],[[2,4],[5]]];
fillArray(test, 0);

answered Sep 8, 2017 at 22:37

tjgersho

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Comments

Pranay · Accepted Answer · 2016-10-17 12:48:11Z

-1

using map function

var arr = [ 
           [ 7, 9, 10 ], 
           [ 6, 9], 
           [ 5, 9] 
       ]

       var arr1 = arr.map(function(e){
       var arr2 = [];
        if(e.length < 3)
            e.push(0);

         arr2.push(e);
         return arr2;

       });

      alert(arr1);

answered Oct 17, 2016 at 12:48

Pranay

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