CODEWITHSUNDEEP
javascript
John
John

Reputation: 1665

group array of objects by id

I am trying to loop through a array ob objects and group the items of the array into new arrays that have matching id:

API example:

    api_array [
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   ];

I am trying to achieve this result:

result [
group_one [
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
]
group_two [
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
]
group_three [
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
]
group_four [
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
]
]

I have actually managed to achieve it but i think its crazy and am sure there is a better implementation here is what i have done:

const createAddresses = (address) => {


        let group_one= [],
        group_two = [],
        group_three = [],
        group_four = [],
          group = [];

        debugger;
        for(let i=0; i < address.length; i++) {             
            switch (address[i].id) {
                case 1:
                        group_one.push(address[i]);
                    break;
                case 2:
                        group_two.push(address[i]);
                    break;
                case 3:
                        group_three.push(address[i]);
                    break;
                case 4:
                        group_four.push(address[i]);
                    break;
                default:
                    return address;                
            }
        }



        console.log('GROUP', group);
        return group.push(group_one, group_two, group_three, group_four);
    }

I really dont like this implementation and have tried this:

const obj = address.reduce((acc, cur) => ({...acc, [cur.id]: cur}), {});

and what the above does is the same as my insane for loop function but it only adds last element for each group like so:

result [
    0 [
           {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    ]
    1 [
           {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    ]
    2 [
           {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    ]
    3 [`enter code here`
           {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    ]
    ]

but like i have mentioned i need all the elements in side each group any advice please.

Upvotes: 1

Views: 13245

Answers (9)

leteu
leteu

Reputation: 171

you can use reduce to grouping like this.

const api_array = [
   {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
 ];

function groupingApiArr(arr) {
  return arr.reduce((acc, cur) => {
    const groupKey = `group-${cur.id}`
  
    if (!acc[groupKey]) {
      acc[groupKey] = []
    }
    
    acc[groupKey].push(cur)
    
    return acc
  }, {})
}

console.log(groupingApiArr(api_array))

Upvotes: 0

Buzzinga
Buzzinga

Reputation: 401

var objs = [
   { id: 1, postcode: "xxx", street: "xxx", city: "xxx" },
   { id: 1, postcode: "xxx", street: "xxx", city: "xxx" },
   { id: 2, postcode: "xxx", street: "xxx", city: "xxx" },
   { id: 3, postcode: "xxx", street: "xxx", city: "xxx" }
];

var result = objs.reduce(function(r, a) {
  r[a.id] = r[a.id] || [];
  r[a.id].push(a);
  return r;
}, Object.create(null));

console.log(result);

Upvotes: 4

Pavel Sem
Pavel Sem

Reputation: 1753

https://jsfiddle.net/u4k16ojz/5/

var result = new Array(4);
api_array.forEach(function(item, index){
  if (!result[item.id]){
    result[item.id] = [];
  }
  result[item.id].push(item);
})

Upvotes: 2

Richard Rowell
Richard Rowell

Reputation: 318

group array of objects by id

//Create a javascript array of objects containing key value pairs id, post 
var api_array = [ 
       {id: 1, postcode: '10'}, 
       {id: 1, postcode: '11'}, 
       {id: 2, postcode: '20'}, 
       {id: 2, postcode: '21'}, 
       {id: 2, postcode: '22'}, 
       {id: 3, postcode: '30'} 
   ];  
//result is a javascript array containing the groups grouped by id. 
let result = []; 

//javascript array has a method foreach that enumerates keyvalue pairs. 
api_array.forEach(  
    r => { 
        //if an array index by the value of id is not found, instantiate it. 
        if( !result[r.id] ){  
            //result gets a new index of the value at id. 
            result[r.id] = []; 
        } 
        //push that whole object from api_array into that list 
        result[r.id].push(r); 
    }   
); 
console.log(result[1]); 
console.log(result[2]); 
console.log(result[3]);

Prints:

[ { id: 1, postcode: '10' }, { id: 1, postcode: '11' } ]

[ { id: 2, postcode: '20' }, 
  { id: 2, postcode: '21' },
  { id: 2, postcode: '22' } ]

[ { id: 3, postcode: '30' } ]

Upvotes: 5

Bilal Siddiqui
Bilal Siddiqui

Reputation: 3629

Try to acheive like this:

 

  var api_array = [
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
   ];
   
  const result = api_array.reduce((acc, item) => {
    acc[`group_${item.id}`] = (acc[`group_${item.id}`] || []);
    acc[`group_${item.id}`].push(item);
    return acc;
  }, {});

console.log(result);

Note: The result will have keys group_1, group_2 ... instead group_one, group_two ...

If you strictly need that, then make an array for key and values to convert 1 as one.

Upvotes: 2

bcr666
bcr666

Reputation: 2197

You could use the ids as properties of an object

let api_array = [
    {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
    {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
];

let grouped = groupArray(api_array);

console.log(grouped);
console.log(grouped[1]);

function groupArray(myArray) {
    let grouped = {};

    for (let i = 0; i < myArray.length; i++) {
        let row = myArray[i];
        let group = grouped[row.id];
        if (!group) {
            group = [];
            grouped[row.id] = group;
        }
        group.push(row);
    }

    return grouped;
}

Upvotes: 0

Thomas Preston
Thomas Preston

Reputation: 707

api_array [
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
       {id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},
];

let result = [];
for (let i = 0; i < numberOfGroupsIWantToMake; i++) {
    let newGroupArray = api_array.filter(obj => obj.id === i);
    result.push(newGroupArray);
}

return result;

Note: this is A solution, but it's not as performant as we're going over the entire array n number of times.

Upvotes: -1

Andy
Andy

Reputation: 63524

Similar to your reduce example, this iterates over the data and creates a object using the object ids as keys and grouping them together. It then grabs the values from that object.

const api_array = [{id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'},{id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx'}];

const out = Object.values(api_array.reduce((acc, c) => {
  const { id } = c;

  // If the object doesn't have a key that matches the id
  // create an array as its value and then concat the current object
  // to it, otherwise, if the key exists just concat the current object
  // to the existing array
  acc[id] = (acc[id] || []).concat(c);
  return acc;
}, {}));

console.log(out)

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386654

You could take a Map for grouping same id and get the values from the map as result set.

The result set has the same order of the wanted keys.

function groupBy(array, key) {
    return Array.from(array
        .reduce((m, o) => m.set(o[key], [...(m.get(o[key]) || []), o]), new Map)
        .values()
    );
}

var data = [{ id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 1, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 2, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 3, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx' }, { id: 4, postcode: 'xxx', street: 'xxx', city: 'xxx' }],
    grouped = groupBy(data, 'id');

console.log(grouped);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 1

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