Assign array elements among 3 variables in jquery

Question

I have the following array:

var Set = ("BENELUX,Luxembourg,PP3a,Western_Europe,France,PP6a").split(',');

Working sequentially, I'd like to take 3 elements at a time and assign each to a variable. The result I'd like is:

var Aggreg = ["BENELUX", "Western Europe"]
var Country = ["Luxembourg", "France"] 
var Product = ["PP3a", "PP6a"]

The order of elements in 'Set' will always be sequential and will always be a multiple of 3. I'm sure there's a clever, efficient way to do this. Anyone able to point me in the right direction?

And do you want a single string in the arrays, like ["BENELUX, Western Europe"], or do you want each element as it's own string, like ["BENELUX", "Western Europe"]? — mhodges
– mhodges, Commented Sep 29, 2017 at 16:13
@Silverburch Check to see if my answer gives the output you're looking for. — mhodges
– mhodges, Commented Sep 29, 2017 at 16:20

guest271314 · Accepted Answer · 2018-01-10 03:27:27Z

2

You can use destructuring assignment, increment variables to reflect indexes

var set = "BENELUX,Luxembourg,PP3a,Western_Europe,France,PP6a".split(",");

var n = 0, m = 3;

var fn = (arr, a = 0, b = 3) => [arr[a], arr[b]];

var [Aggreg, Country, Product] = [
  fn(set),
  fn(set, ++n, ++m),
  fn(set, ++n, ++m)
];

console.log(Aggreg, Country, Product);

alternatively

var set = "BENELUX,Luxembourg,PP3a,Western_Europe,France,PP6a".split(",");

var fn = function* (arr) {
  var n = 0, m = 3;
  while (m < arr.length) {
    yield [arr[n], arr[m]];
    n += 1; m += 1;
  }
};

var [Aggreg, Country, Product] = fn(set);

console.log(Aggreg, Country, Product);

edited Jan 10, 2018 at 3:27

answered Sep 29, 2017 at 16:14

guest271314

1

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5 Comments

mhodges Over a year ago

re check the desired output. Aggreg should be every 3n, Country every 3n+1 and Product every 3n+2

mhodges Over a year ago

"Set will always be a multiple of 3" implies to me that it can have 3n number of elements, this solution only handles 6 elements

guest271314 Over a year ago

@mhodges Not following what you mean?

mhodges Over a year ago

This doesn't handle more than 6 elements in Set

guest271314 Over a year ago

@mhodges How so?

mhodges · Accepted Answer · 2017-09-29 16:19:52Z

1

You can use .reduce() to get each part into an array inside a single object, and then use a destructuring assignment to assign individual variables, like so:

var Set = ("BENELUX,Luxembourg,PP3a,Western_Europe,France,PP6a").split(',');

var {Aggreg, Country, Product} = Set.reduce(function (result, curr, index) {
  if (index % 3 === 0) {
    result.Aggreg.push(curr);
  }
  else if (index % 3 === 1) {
    result.Country.push(curr);
  }
  else {
    result.Product.push(curr);
  }
  return result;
}, {Aggreg: [], Country: [], Product: []})

console.log(Aggreg);
console.log(Country);
console.log(Product);

answered Sep 29, 2017 at 16:19

mhodges

11.2k2 gold badges32 silver badges48 bronze badges

5 Comments

soywod Over a year ago

A bit too complicated IMO

mhodges Over a year ago

@soywod It does the exact same thing yours does, just with 1 iteration of the array, rather than 3. Reduce is a pretty common looping structure in JavaScript - not sure what is complicated here

Tyler Roper Over a year ago

Why the downvote? (Not my answer, but this answer is correct...)

Silverburch Over a year ago

I don't understand the downvote either. The single iteration of the array is exactly what I need given that 'Set' could potentially be big. Much appreciated.

mhodges Over a year ago

@Silverburch You're welcome. If you found this answer helpful, be sure to upvote and mark as accepted.

soywod · Accepted Answer · 2017-09-29 16:27:41Z

1

Just filter your array using the modulo (if you are sure about your data - in this case, be sure to get a multiple of 3 array size) :

const data = "BENELUX,Luxembourg,PP3a,Western_Europe,France,PP6a".split(",")

function extract(data, shift) {
  return data.filter((value, index) => (index % 3) === shift)
}

const Aggreg = extract(data, 0)
const Country = extract(data, 1)
const Product = extract(data, 2)

console.log(Aggreg, Country, Product)

edited Sep 29, 2017 at 16:27

answered Sep 29, 2017 at 16:18

soywod

4,5784 gold badges29 silver badges50 bronze badges

Comments

Tyler Roper · Accepted Answer · 2017-09-29 18:47:00Z

1

Could make use of a simple Array.prototype.forEach():

var Set = "BENELUX,Luxembourg,PP3a,Western_Europe,France,PP6a".split(',');

var Aggreg = [],
    Country = [],
    Product = [];


Set.forEach(function(item, index) { //For each item in the array
  switch (index % 3) {              //Get remainder of index/3
    case 0:
      Aggreg.push(item);            //If 0, Aggreg
      break;
    case 1:
      Country.push(item);           //If 1, Country
      break;
    case 2:
      Product.push(item);           //If 2, Product
  }
})

console.log(Aggreg, Country, Product);

edited Sep 29, 2017 at 18:47

answered Sep 29, 2017 at 16:22

Tyler Roper

21.7k6 gold badges35 silver badges58 bronze badges

3 Comments

Tyler Roper Over a year ago

A downvote on a correct answer. Welcome to Stack Overflow :)

mhodges Over a year ago

Not a huge fan of impure functions, but I will upvote for a correct answer and to offset the random downvote. lol

Tyler Roper Over a year ago

@mhodges Appreciated! I do somewhat regret littering the scope but oh well, I guess it's got readability going for it :P

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