javascript - Divide array into multiple arrays - Stack Overflow

I have the following two arrays:

var arr1 = [1,2,4,5];
var arr2 = [];

How would I go about to split it when there is no consecutive value?

In this example, it should be split into: [ [1,2] and [4,5].

These two arrays should be stored in arr2.

Example 2 :

var arr3 = [1,2,3,5,6,7,8,9,10,11,13]

Result : [[1,2,3], [5,6,7,8,9,10], [11], [13]]

I have the following two arrays:

var arr1 = [1,2,4,5];
var arr2 = [];

How would I go about to split it when there is no consecutive value?

In this example, it should be split into: [ [1,2] and [4,5].

These two arrays should be stored in arr2.

Example 2 :

var arr3 = [1,2,3,5,6,7,8,9,10,11,13]

Result : [[1,2,3], [5,6,7,8,9,10], [11], [13]]

• javascript
• arrays

Share Improve this question Follow edited Sep 19, 2016 at 13:02 Karthik VU 56155 silver badges1818 bronze badges asked Sep 19, 2016 at 11:56 Konstantin HadzhievKonstantin Hadzhiev 1951313 bronze badges 3

• And then what? How would you want that to be stored? – Cerbrus Commented Sep 19, 2016 at 11:57
• Ah I'm sorry. I wasn't clear enough - i see now. I would store it in an array which holds these arrays. I`ll write that in the main question now :) – Konstantin Hadzhiev Commented Sep 19, 2016 at 11:58
• 1 This conversation might help you: Split array into chunks - StackOverflow – op_ Commented Sep 19, 2016 at 12:01

Add a ment  | 

5 Answers 5

Sorted by: Reset to default 7

You could use Array#reduce and check if the element is consecutive. Then append to the last array, otherwise push a new array to the result set.

var array = [1, 2, 4, 5],
    result = array.reduce(function (r, a, i, aa) {
        if (!i || aa[i - 1] + 1 !== a) {
            r.push([a]);
        } else {
            r[r.length - 1].push(a);
        }
        return r;
    }, []);

console.log(result);

Here is a way to do it :

var arr1 = [1,2,4,5];

var slices = [];
var sliceNb = 0;
arr1.forEach(function(v, k, arr){
	if(!slices[sliceNb]){
		slices[sliceNb] = [];
	}
	slices[sliceNb].push(v);

	if(arr[k+1] && arr[k+1] > v+1){
		sliceNb++;
	}
});

console.log(slices);

try this:

arr1 = [1,2,3,4]
new_arr = [arr1.slice(0, (arr1.length/2) ), arr1.slice(arr1.length/2 +1, arr1.length)]
new_arr
//[[1,2],[3,4]]

You can figure out the chunk size my dividing the size of the array by the number of partitions. Then you can simply slice the array.

var arr1 = [1, 2, 4, 5];
var arr2 = partitionArray(arr1, 2); // [[1, 2], [4, 5]]

document.body.innerHTML = '<pre>arr2 = ' + JSON.stringify(arr2) + '</pre>';

/**
 * Partitions an array into chunks.
 * @param  {Array}  arr - The array to partition.
 * @param  {int}    n   - The number of partitions. 
 * @return {Array} Returns a partitioned array.
 */
function partitionArray(arr, n) {
  var chunkSize = Math.max(arr.length / n, 1);
  return [].concat.apply([], arr.map(function(item, i) {
    return i % chunkSize ? [] : [arr.slice(i, i + chunkSize)];
  }));
}

You might do as follows;

var arr = [1,2,4,5,6,111,111,112],
    res = arr.reduce((p,c,i,a) => c === a[i-1]+1 ? (p[p.length-1].push(c),p) 
                                                 : p.concat([[c]]),[]);
console.log(res);