CODEWITHSUNDEEP
javascript
flawr
flawr

Reputation: 11628

shortest way to create 2d array certain size

What is the shortest way to create a 2d array of a certain size?

I figured that following code is pretty short, but can you do it with even less code?

var x = 5;
var y = 7;
var my2dArray = (new Array(y)).fill(0).map(
                                            function(){
                                               return new Array(x);
                                            }
                                          );

Upvotes: 1

Views: 3017

Answers (2)

user663031
user663031

Reputation: 

Array.apply(0, Array(x)).map(function() { return Array.apply(0, Array(y)); })

Simpler if you write a little convenience routine

function make_array(x) { return Array.apply(0, Array(x)); }

then

make_array(x).map(function() { return make_array(y);} )

or if you prefer

make_array(x).map(make_array.bind(0, y))

If you're writing ES6:

Array(...Array(x)).map(() => Array(y));

If you'd prefer to use fill, since you seem to have it available:

Array(x).fill().map(function() { return Array(y); });

or somewhat more concisely in ES6, using an arrow function:

Array(x).fill().map(() => Array(y));

It turns out Array#fill requires no argument; without it, it replaces absent elements with undefineds.

Upvotes: 11

GameAlchemist
GameAlchemist

Reputation: 19294

What about building your own Class ? 

function Array2D(xSize, ySize, initialValue) {
  initialValue=initialValue || 0;
  // create an flat empty array filled with the initial value 
  var length = xSize*ySize;
  var innerArray = new Array(length);
  for (var i=0; i<length; i++) innerArray[i] = initialValue;
  // accessors
  this.getAt = function(x, y) { return innerArray[x+xSize*y]};
  this.setAt = function(x, y, val) { innerArray[x+xSize*y]=val};
}

Use with :

var myArray2d = new Array2D(5,7);

myArray2d.setAt(1,1,3);
var value = myArray2d.getAt(1,1);        // == 3
var anotherValue = myArray2d.getAt(2,2); // == 0

Upvotes: 3

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