JavaScript: How to push data in array, into subarrays with an array for each 16 items

Question

I have an example data set. I want to push this data into an array with a subarray for every 16 pieces of data. I got started, but am stuck. Any ideas?

[ [16 names], [16 names ], [16 names] ]; // This is the output I want.

var data = ["Michael", "Marc", "John", "David", "Nick", "Mom", "Al", "Marlana", "Max", 
            "Scooter", "Pat", "George", "Lynne", "Tatyana", "Kim", "Kerry", "Enza", "Matt",
            "Liz", "Linda", "Ryan",
            "Ed", "Frank", "Christine", "Bill", "Jack", "Jill", "Joe", "Harry", "Red",
            "Fred", "Iggy", "Brian", "Bob", "Paul", "Gil", "Damian", "Kip", "Phil", "Curtis", "Aly",
           "Richard", "Robin", "Grant", "Ian", "Raptor", "T-Rex", "Stegosaurux", "Triceratops", "Compy"]


var sixteengroup = [];

for (var i = 0; i < data.length; i++){
  if (i % 16 == 0) sixteengroup.push([i])
}


console.log(sixteengroup);

do you want to put the first 16 into one array, the next 16 into another, and so on, or do you want the 1st, 17th, 33th, in the first, 2nd, 18th, 34th in the second and so on? — Transcendence, Apr 24 '15 at 21:00

mplungjan · Accepted Answer · 2015-04-24T21:46:14.177

3

Splice (destructive) or slice sounds like a good idea

var data = ["Michael", "Marc", "John", "David", "Nick", "Mom", "Al", "Marlana", "Max","Scooter", "Pat", "George", "Lynne", "Tatyana", "Kim", "Kerry", "Enza", "Matt","Liz", "Linda", "Ryan", "Ed", "Frank", "Christine", "Bill", "Jack", "Jill", "Joe", "Harry", "Red", "Fred", "Iggy", "Brian", "Bob", "Paul", "Gil", "Damian", "Kip", "Phil", "Curtis", "Aly", "Richard", "Robin", "Grant", "Ian", "Raptor", "T-Rex", "Stegosaurux", "Triceratops", "Compy"]

function chunk(source,size) { // non-destructive
  var arrofarr=[], cnt=0;
  while (cnt < source.length) { 
    arrofarr.push(source.slice(cnt,cnt+size)); 
    cnt+= arrofarr[arrofarr.length-1].length;
  }
  return arrofarr;
}  
console.log(chunk(data,16));

// ----------------------------------

function chunkie(source,size) { // destructive
  var arrofarr=[];
  while (source.length) { arrofarr.push(source.splice(0,size)); }
  return arrofarr;
}
console.log(chunkie(data,16));

edited Apr 24 '15 at 21:46

answered Apr 24 '15 at 21:02

mplungjan

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I wanted splice, not slice :) – mplungjan Apr 24 '15 at 21:06
1

Looks like two names got dropped. There's 50 names in the list; you're only returning 48 (divisible by 16). – bloodyKnuckles Apr 24 '15 at 21:10
You want `Math.ceil`, not `parseInt`. – Evan Davis Apr 24 '15 at 21:13
4

Simpler: `while(data.length) sixteengroup.push(data.splice(0,16));` – Rick Hitchcock Apr 24 '15 at 21:14
Fixed the overflow - use while instead as I should have. Very late here :) – mplungjan Apr 24 '15 at 21:15
Why would you use `parseInt` on something that is already guaranteed to be a number though? – Evan Davis Apr 24 '15 at 21:15
I am mind blown that is considered a correct answer. Have you seen this? http://stackoverflow.com/questions/8495687/split-array-into-chunks – Arnaldo Capo Apr 26 '15 at 20:48
@ArnaldoCapo What is the issue? That I renamed my functions to use the word chunk after I found the duplicate after I had coded the same thing? You do realise the link you gave is the one I closed the question with? – mplungjan Apr 26 '15 at 21:02

score 1 · Answer 2 · answered Apr 24 '15 at 21:06

Try this:

var data = ["Michael", "Marc", "John", "David", "Nick", "Mom", "Al", "Marlana", "Max", 
        "Scooter", "Pat", "George", "Lynne", "Tatyana", "Kim", "Kerry", "Enza", "Matt",
        "Liz", "Linda", "Ryan",
        "Ed", "Frank", "Christine", "Bill", "Jack", "Jill", "Joe", "Harry", "Red",
        "Fred", "Iggy", "Brian", "Bob", "Paul", "Gil", "Damian", "Kip", "Phil", "Curtis", "Aly",
       "Richard", "Robin", "Grant", "Ian", "Raptor", "T-Rex", "Stegosaurux", "Triceratops", "Compy"]


var sixteengroup = [];

var x = -1;
for (var i = 0; i < data.length; i++){

    if (i % 16 == 0) {
        sixteengroup[++x] = [data[i]]
        continue;
    } 

    sixteengroup[x].push(data[i])

}

console.log(sixteengroup);

Fiddle here: https://jsfiddle.net/n9ro2vwr/1/

Please expand on why so that in the future I avoid inefficiency. Maybe the world a better place. — Arnaldo Capo, Apr 26 '15 at 20:46
You add them one by one. Then you complain my splice/slice suggestion was accepted? I abandoned the loop I wrote about 5 minutes before you wrote yours — mplungjan, Apr 26 '15 at 21:04

score 0 · Answer 3 · answered Apr 24 '15 at 21:01

Try the following:

function split(a, n) {
    var len = a.length,out = [], i = 0;
    while (i < len) {
        var size = Math.ceil((len - i) / n--);
        out.push(a.slice(i, i += size));
    }
    return out;
}
var data = ["Michael", "Marc", "John", "David", "Nick", "Mom", "Al", "Marlana", "Max", 
            "Scooter", "Pat", "George", "Lynne", "Tatyana", "Kim", "Kerry", "Enza", "Matt",
            "Liz", "Linda", "Ryan",
            "Ed", "Frank", "Christine", "Bill", "Jack", "Jill", "Joe", "Harry", "Red",
            "Fred", "Iggy", "Brian", "Bob", "Paul", "Gil", "Damian", "Kip", "Phil", "Curtis", "Aly",
           "Richard", "Robin", "Grant", "Ian", "Raptor", "T-Rex", "Stegosaurux", "Triceratops", "Compy"]

sixteengroup = split(data, data.length/16);
document.write(JSON.stringify(sixteengroup));

That is a lot of code to reinvent slice – mplungjan Apr 24 '15 at 21:04 — mplungjan, Apr 24 '15 at 21:04

A.B · Answer 4 · 2015-04-24T21:23:11.890

0

i use this function to group by any number

  groupBy = function (array,howmany)
    {
    var newarray =[];
    index=0;
    for(a=0;a<array.length;a++){
       if(a%howmany==0){
          if(a!=0)
           index++;               
          newarray[index]=[];
          newarray[index].push(array[a]);

      }else{
         newarray[index].push(array[a]);

      }
   }
  return newarray;
}

 items=groupBy(data,16);

edited Apr 24 '15 at 21:23

answered Apr 24 '15 at 21:02

A.B

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You could simplify that logic quite a bit. – Evan Davis Apr 24 '15 at 21:04
@Mathletics i really need to, seems like i am still bad at making algos.. – A.B Apr 24 '15 at 21:07
Well `0 % n // 0` so you don't need the `a==0` check. – Evan Davis Apr 24 '15 at 21:09
ohkie, thanks i am editing. one question out of context, is it experience, iq or knowledge that lacks making these stuff right? @Mathletics – A.B Apr 24 '15 at 21:12

score 0 · Answer 5 · answered Apr 24 '15 at 21:10

maybe make a function with 2 arguments to have the array and the second argument to limit the amount of items per second denominational array like so?

function data(arr, size) {
  var array = [];
    while(arr.length > 0){
         array.push(arr.splice(0,size));   
    }
  return console.log(array);
}

data(["Michael", "Marc", "John", "David", "Nick", "Mom", "Al", "Marlana", "Max", 
            "Scooter", "Pat", "George", "Lynne", "Tatyana", "Kim", "Kerry", "Enza", "Matt",
            "Liz", "Linda", "Ryan",
            "Ed", "Frank", "Christine", "Bill", "Jack", "Jill", "Joe", "Harry", "Red",
            "Fred", "Iggy", "Brian", "Bob", "Paul", "Gil", "Damian", "Kip", "Phil", "Curtis", "Aly",
           "Richard", "Robin", "Grant", "Ian", "Raptor", "T-Rex", "Stegosaurux", "Triceratops", "Compy"], 16)

https://jsfiddle.net/ToreanJoel/dq7t7snx/

You can play around and see if its to your liking.

JavaScript: How to push data in array, into subarrays with an array for each 16 items

5 Answers5