Create arrays from 1D array after every nth occurrence using Angular JS

Question

I have an array which looks like this

Array[20]
0 : "2"
1 : "3"
2 : "4"
3 : "5"
4 : "6"
5 : "7"
6 : "8"
7 : "9"
8 : "10"
9 : "11"
10: "12"
11: "13"
12: "14"
13: "15"
14: "16"
15: "17"
16: "18"
17: "19"
18: "20"
19: "12"

Now I want to create arrays after every 4th occurrence like this

First Array

0 : "2"
1 : "6"
2 : "10"
3 : "14"
4 : "18"

Second Array

0 : "3"
1 : "7"
2 : "11"
3 : "15"
4 : "19"

and so on...

Yet I have written this code

for (var i = 0; i < $scope.data.effort.length; i = i+ 4) {
    efforts.push( $scope.data.effort[i]);
 };

From above code I am getting only first array what should I need to do to get remaining arrays. Please help

tanmay · Accepted Answer · 2017-04-12 07:19:49Z

2

All you need is to run an extra loop outside that which handles your starting index. LIke this:

efforts = []
for (var j = 0; j < arr.length / 4; j++) {
  efforts[j] = []
  for (var i = j; i < arr.length; i = i + 4) {
    efforts[j].push(arr[i]);
  };
  console.log(efforts[j])
}

Here's working example: (simplified in JS, without $scope and all)

var arr = [
  "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14",
  "15", "16", "17", "18", "19", "20", "12"
]
efforts = []
for (var j = 0; j < arr.length / 4; j++) {
  efforts[j] = []
  for (var i = j; i < arr.length; i = i + 4) {
    efforts[j].push(arr[i]);
  };
  console.log(efforts[j])
}

Or, interestingly, you can use the beast, I mean, reduce to achieve the same. :)

var arr = [
  "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14",
  "15", "16", "17", "18", "19", "20", "12"
]
efforts = arr.reduce(function(arr, cur, curIndex) {
  arr[curIndex % 4] = arr[curIndex % 4] || [];
  arr[curIndex % 4].push(cur);
  return arr
}, [])
console.log(efforts)

edited Apr 12, 2017 at 7:19

answered Apr 12, 2017 at 7:07

tanmay

7,9112 gold badges24 silver badges39 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

tanmay Over a year ago

@Ramkishan glad I could help :)

Ramkishan Suthar Over a year ago

Let me try this

Ramkishan Suthar Over a year ago

Yes it is really interesting from the first one. once again thanks.

Faly · Accepted Answer · 2017-04-12 07:31:31Z

1

Another simple way with array filter:

var originalArray =["2","3","4","5","6","7","8","9","10","11","12","13","14","15","16","17","18","19","20","21"];           
var firstArray = originalArray.filter((el, index) => (index%4 === 0));
var secondArray = originalArray.filter((el, index) => (index%4 === 1));

and so on

edited Apr 12, 2017 at 7:31

answered Apr 12, 2017 at 7:24

Faly

13.4k2 gold badges21 silver badges39 bronze badges

Collectives™ on Stack Overflow

Create arrays from 1D array after every nth occurrence using Angular JS

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related