Refactor to use reduce for grouping array of objects by nested array text

Question

I have a function that will accept 3 arguments; an array of data, a key and a partial value. I want to group the results by a value that may be in each objects nested array. It looks like my code is working, but I'm wondering if refactoring to use reduce would be better. Here is what I have:

const arr = [
  {
    "id": "vghjnbghjkoijhjnmkjhjk",
    "region": "US",
    "tags": ["tag1:bvghjhgh","tag2:bvghjkjnm","tag3:vghjbghj"]
  },
  {
    "id": "cvbhyt56789-mnbvghyu76",
    "region": "US",
    "tags": ["tag1:bvghjhgh"]
  },
  {
    "id": "ghjkjnbhjnbhjkmnhjkmjk",
    "region": "US",
    "tags": ["tag2:bvghjkjnm"]
  },
  {
    "id": "ghjkjnbhjnbhjkmnhjkmjk",
    "region": "US",
    "tags": []
  },
  {
    "id": "bghjkjnbghjkjnhjnbhjhj",
    "region": "CA",
    "tags": ["tag1:bvghjhgh","tag3:vghjbghj"]
  }
];

The expected results are as follows, based on a key of tags and a value of tag1:

[
  [
    {
      "id": "vghjnbghjkoijhjnmkjhjk",
      "region": "US",
      "tags": ["tag1:bvghjhgh","tag2:bvghjkjnm","tag3:vghjbghj"]
    },
    {
      "id": "cvbhyt56789-mnbvghyu76",
      "region": "US",
      "tags": ["tag1:bvghjhgh"]
    },
    {
      "id": "bghjkjnbghjkjnhjnbhjhj",
      "region": "CA",
      "tags": ["tag1:bvghjhgh","tag3:vghjbghj"]
    }
  ],
  [
      {
        "id": "ghjkjnbhjnbhjkmnhjkmjk",
        "region": "US",
        "tags": ["tag2:bvghjkjnm"]
      },
      {
        "id": "ghjkjnbhjnbhjkmnhjkmjk",
        "region": "US",
        "tags": []
      },
  ]
]

Here is my current function:

function groupData(arr, key, value) {
  const grouped = {};
  const remaining = [];

  for (const obj of arr) {
    const index = obj[key].findIndex(elem => elem.includes(value));  
    if (index > -1) {
      const groupByKey = obj[key][index];
      if (grouped.hasOwnProperty(groupByKey)) {
        grouped[groupByKey].push(obj);
      } else {
        grouped[groupByKey] = [obj];
      }
    } else {
      remaining.push(obj);
    }
  }

  return [Object.values(grouped).flat(), noMatch];
}

flyingfox · Accepted Answer · 2022-10-20 03:19:06Z

I provide a solution using reduce() and map,but compared with other answers,seems groupby is a better choice

const arr = [
  {
    "id": "vghjnbghjkoijhjnmkjhjk",
    "region": "US",
    "tags": ["tag1:bvghjhgh","tag2:bvghjkjnm","tag3:vghjbghj"]
  },
  {
    "id": "cvbhyt56789-mnbvghyu76",
    "region": "US",
    "tags": ["tag1:bvghjhgh"]
  },
  {
    "id": "ghjkjnbhjnbhjkmnhjkmjk",
    "region": "US",
    "tags": ["tag2:bvghjkjnm"]
  },
  {
    "id": "ghjkjnbhjnbhjkmnhjkmjk",
    "region": "US",
    "tags": []
  },
  {
    "id": "bghjkjnbghjkjnhjnbhjhj",
    "region": "CA",
    "tags": ["tag1:bvghjhgh","tag3:vghjbghj"]
  }
];

let mdata = {'tags':'tag1'}
let entries = Object.entries(mdata).flat()
let key = entries[0],value = entries[1]

let result = arr.reduce((a,c) => {
 let exists = c[key].some(i => i.startsWith(value + ':'))
 let skey = exists ? value: 'other'
 let obj = a.find(a => a[skey])
 if(obj){
   obj[skey].push(c)
 }else{
   obj = {[skey]:[c]}
   a.push(obj)
 }
 return a
},[])

result = result.map(d => d[value]||d.other)
console.log(result)

Ry- · Accepted Answer · 2022-10-20 01:42:14Z

0

A generic groupBy (similar functions exist in popular libraries like LoDash) would help here:

const groupBy = (iterable, keyFn) => {
    const groups = new Map();
    for (const x of iterable) {
        const key = keyFn(x);
        let group = groups.get(key);
        if (group === undefined) {
            groups.set(key, group = []);
        }
        group.push(x);
    }
    return groups;
};

Then you have:

const groupData = (arr, key, value) => {
    const groups = groupBy(arr, obj =>
        obj[key].find(elem => elem.includes(value)));

    const noMatch = groups.get(undefined);
    groups.delete(undefined);

    return [[...groups.values()].flat(), noMatch];
};

answered Oct 20, 2022 at 1:42

community wiki

Ry-

Collectives™ on Stack Overflow

Refactor to use reduce for grouping array of objects by nested array text

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related