All possible combinations with data from JSON file

Question

My goal is to create a part of code that would generate all possible combinations without duplicates (combinations with same elements, no matter what their sequence is) with data from a JSON file. My JSON file looks like this:

[
 {
   "COLLECTION": "Assault",
   "WEAPON": "SG 553",
   "SKIN": "Tornado",
   "GRADE": "Consumer Grade"
 },
 {
   "COLLECTION": "Assault",
   "WEAPON": "UMP-45",
   "SKIN": "Caramel",
   "GRADE": "Consumer Grade"
 },
 {
   "COLLECTION": "Vertigo",
   "WEAPON": "Five-SeveN",
   "SKIN": "Candy Apple ",
   "GRADE": "Industrial Grade"
 }, ...
]

Combinations would be generated in the following way:

[
    "COMBINATION 1":[
     {
       "COLLECTION": "Assault",
       "WEAPON": "SG 553",
       "SKIN": "Tornado",
       "GRADE": "Consumer Grade"
     },
     {
       "COLLECTION": "Assault",
       "WEAPON": "UMP-45",
       "SKIN": "Caramel",
       "GRADE": "Consumer Grade"
     },
     {
       "COLLECTION": "Assault",
       "WEAPON": "Five-SeveN",
       "SKIN": "Candy Apple ",
       "GRADE": "Industrial Grade"
     }, ...
    ],

    "COMBINATION 2":[
     {
       "COLLECTION": "Assault",
       "WEAPON": "SG 553",
       "SKIN": "Tornado",
       "GRADE": "Consumer Grade"
     },
    {
       "COLLECTION": "Aztec",
       "WEAPON": "M4A4",
       "SKIN": "Jungle Tiger",
       "GRADE": "Industrial Grade"
     },
     {
       "COLLECTION": "Aztec",
       "WEAPON": "Tec-9",
       "SKIN": "Ossified",
       "GRADE": "Mil-Spec"
     }, ...
    ],...
]

Note that in this case both combinations have the same elements and therefore shouldn't be noted twice. That means that as long as there are elements in a combination that are same to another possible combination (no matter what sequence they are in) it counts as one combination (every combination will have 10 elements, and would be distinct from another based on the "SKIN" attribute values):

[
    "COMBINATION 1":[
     {
       "COLLECTION": "Vertigo",
       "WEAPON": "SG 553",
       "SKIN": "Tornado",
       "GRADE": "Consumer Grade"
     },
     {
       "COLLECTION": "Assault",
       "WEAPON": "UMP-45",
       "SKIN": "Caramel",
       "GRADE": "Consumer Grade"
     },
     {
       "COLLECTION": "Assault",
       "WEAPON": "Five-SeveN",
       "SKIN": "Candy Apple ",
       "GRADE": "Industrial Grade"
     },...
    ],

    "COMBINATION 2":[
    {
       "COLLECTION": "Assault",
       "WEAPON": "Five-SeveN",
       "SKIN": "Candy Apple ",
       "GRADE": "Industrial Grade"
     },
      {
       "COLLECTION": "Vertigo",
       "WEAPON": "SG 553",
       "SKIN": "Tornado",
       "GRADE": "Consumer Grade"
     },
     {
       "COLLECTION": "Assault",
       "WEAPON": "UMP-45",
       "SKIN": "Caramel",
       "GRADE": "Consumer Grade"
     },...
],...

Also note that the same item can appear in a combination multiple times (up to 10) and that I'm workig with a JSON file of around 1500 elements, so efficiency is key. To sum it up the final product should look something like this: https://textuploader.com/1du6o

This is also a kinda similar problem, but less complex: Permutations in JavaScript?

I've tried to sort this out with bubble sort and such, but haven't succeeded thus far. If you have any ideas how to make this happen I'd love to hear them.

score 1 · Accepted Answer · answered Jun 17 '19 at 17:21

Although it's not entirely clear how to determine combinations the way you suggest, this might get you part of the way there.

Create a data structure to store unique elements for collection, weapon, skin, and grade:

// JSON sources.
const sources = [
  {
    "COLLECTION": "Assault",
    "WEAPON": "SG 553",
    "SKIN": "Tornado",
    "GRADE": "Consumer Grade"
  },
  {
    "COLLECTION": "Assault",
    "WEAPON": "UMP-45",
    "SKIN": "Caramel",
    "GRADE": "Consumer Grade"
  },
  {
    "COLLECTION": "Vertigo",
    "WEAPON": "Five-SeveN",
    "SKIN": "Candy Apple ",
    "GRADE": "Industrial Grade"
  },
]

// Create storage for the sources. Use sets to prevent duplicates.
const map = new Map([
  ['COLLECTION', new Set()],
  ['WEAPON', new Set()],
  ['SKIN', new Set()],
  ['GRADE', new Set()]
])

// Load each source into the map.
sources.forEach((source) => {
  Object.keys(source).forEach((key) => {
    const set = map.get(key)
    set.add(source[key])
  })
})

console.log(map)

Output:

Map {
  'COLLECTION' => Set { 'Assault', 'Vertigo' },
  'WEAPON' => Set { 'SG 553', 'UMP-45', 'Five-SeveN' },
  'SKIN' => Set { 'Tornado', 'Caramel', 'Candy Apple ' },
  'GRADE' => Set { 'Consumer Grade', 'Industrial Grade' } }

Generate all combinations from the map's sets by iterating using nested loops:

// Store the generated combinations.
const combinations = []

// Generate all combinations.
for (const collection of map.get('COLLECTION')) {
  for (const weapon of map.get('WEAPON')) {
    for (const skin of map.get('SKIN')) {
      for (const grade of map.get('GRADE')) {
        combinations.push({
          'COLLECTION': collection,
          'WEAPON': weapon,
          'SKIN': skin,
          'GRADE': grade,
        })
      }
    }
  }
}

console.log(combinations.length) // 36

Yes this does help a bit. However I'm looking for an algorithm that will not make combinations with the data itself, but one that will just combine (10 items per combination) all possible listings into an array/object (no duplicates). Note that the same item can be in the combination multiple times (up to 10), but two combinations can't have exactly the same elements, no matter the position or order they are in. Thanks for your help anyway :) — quo91, Jun 17 '19 at 20:14

All possible combinations with data from JSON file

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