Convert a 1D array to 2D array [duplicate]

Question

I am working on a program where I have to read the values from a textfile into an 1D array.I have been succesfull in getting the numbers in that 1D array.

m1=[1,2,3,4,5,6,7,8,9] 

but I want the array to be

m1=[[1,2,3],[4,5,6],[7,8,9]] 

Answer 1

You can use this code :

const arr = [1,2,3,4,5,6,7,8,9];      const newArr = []; while(arr.length) newArr.push(arr.splice(0,3));      console.log(newArr);

http://jsfiddle.net/JbL3p/

Answer 2

Array.prototype.reshape = function(rows, cols) {    var copy = this.slice(0); // Copy all elements.    this.length = 0; // Clear out existing array.      for (var r = 0; r < rows; r++) {      var row = [];      for (var c = 0; c < cols; c++) {        var i = r * cols + c;        if (i < copy.length) {          row.push(copy[i]);        }      }      this.push(row);    }  };    m1 = [1, 2, 3, 4, 5, 6, 7, 8, 9];    m1.reshape(3, 3); // Reshape array in-place.    console.log(m1);

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

Output:

[   [1, 2, 3],   [4, 5, 6],   [7, 8, 9] ] 

JSFiddle DEMO