group array of objects by id

Question

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 [
          


        

Answer 1

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);

Answer 2

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' } ]

Answer 3

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;
}

Answer 4

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.

Answer 5

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.

Answer 6

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);
})