Using Ramda to retrieve objects from an array by comparing them with each element in a separate array

Question

Using Ramda to retrieve objects from an array by comparing them with each element in a separate array

I have two arrays:

ids = [1,3,5];

The second array is:

items: [
{id: 1, name: 'a'}, 
{id: 2, name: 'b'}, 
{id: 3, name: 'c'}, 
{id: 4, name: 'd'}, 
{id: 5, name: 'e'}, 
{id: 6, name: 'f'}
];

I want to create a new array with only the items whose IDs match the ones in the 'ids' array:

array = [{id: 1, name: 'a'}, {id: 3, name: 'c'}, {id: 5, name: 'e'}];

I am struggling to figure this out. I have tried:

console.log(R.filter(R.propEq('id', <don't know what should be here>), items);
console.log( R.pick(ids)(items))

javascript arrays ramda.js

Answer 1

Answer №1

If you are interested in using Ramda, here is an example:

const ids = [1,3,5];

const items = [
{id: 1, name: 'a'}, 
{id: 2, name: 'b'}, 
{id: 3, name: 'c'}, 
{id: 4, name: 'd'}, 
{id: 5, name: 'e'}, 
{id: 6, name: 'f'}
];

console.log(

  R.filter(R.compose(R.flip(R.contains)(ids), R.prop('id')), items)

);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script>

Answer 2

If you are interested in using Ramda, here is an example:

const ids = [1,3,5];

const items = [
{id: 1, name: 'a'}, 
{id: 2, name: 'b'}, 
{id: 3, name: 'c'}, 
{id: 4, name: 'd'}, 
{id: 5, name: 'e'}, 
{id: 6, name: 'f'}
];

console.log(

  R.filter(R.compose(R.flip(R.contains)(ids), R.prop('id')), items)

);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script>

Answer 3

Answer №2

To filter items based on specific ids, you can utilize the .filter and .indexOf methods from ECMAScript 5. Please note that these methods are not compatible with IE8.

var ids = [1, 3, 5];
var items = [
  {id: 1, name: 'a'}, 
  {id: 2, name: 'b'}, 
  {id: 3, name: 'c'}, 
  {id: 4, name: 'd'}, 
  {id: 5, name: 'e'}, 
  {id: 6, name: 'f'}
];

var filteredItems = items.filter(function(obj) {
  return ids.indexOf(obj.id) > -1;
});
console.log(filteredItems); // Outputs: [{id: 1, name: 'a'}, {id: 3, name: 'c'}, {id: 5, name: 'e'}];

Answer 4

To filter items based on specific ids, you can utilize the .filter and .indexOf methods from ECMAScript 5. Please note that these methods are not compatible with IE8.

var ids = [1, 3, 5];
var items = [
  {id: 1, name: 'a'}, 
  {id: 2, name: 'b'}, 
  {id: 3, name: 'c'}, 
  {id: 4, name: 'd'}, 
  {id: 5, name: 'e'}, 
  {id: 6, name: 'f'}
];

var filteredItems = items.filter(function(obj) {
  return ids.indexOf(obj.id) > -1;
});
console.log(filteredItems); // Outputs: [{id: 1, name: 'a'}, {id: 3, name: 'c'}, {id: 5, name: 'e'}];

Answer 5

Answer №3

Perhaps a more concise solution without using Ramda

items.filter(x=>ids.includes(x.id))

Answer 6

Perhaps a more concise solution without using Ramda

items.filter(x=>ids.includes(x.id))

Answer 7

Answer №4

One effective approach is to utilize a hash table for expedited data retrieval.

var ids = [1, 3, 5],
    items = [{id: 1, name: 'a'}, {id: 2, name: 'b'}, {id: 3, name: 'c'}, {id: 4, name: 'd'}, {id: 5, name: 'e'}, {id: 6, name: 'f'} ],
    filtered = items.filter(function(obj) {
        return this[obj.id];
    }, ids.reduce(function (r, a) {
        r[a] = true;
        return r;
    }, Object.create(null)));

document.write('<pre>' + JSON.stringify(filtered, 0, 4) + '</pre>');

Answer 8

One effective approach is to utilize a hash table for expedited data retrieval.

var ids = [1, 3, 5],
    items = [{id: 1, name: 'a'}, {id: 2, name: 'b'}, {id: 3, name: 'c'}, {id: 4, name: 'd'}, {id: 5, name: 'e'}, {id: 6, name: 'f'} ],
    filtered = items.filter(function(obj) {
        return this[obj.id];
    }, ids.reduce(function (r, a) {
        r[a] = true;
        return r;
    }, Object.create(null)));

document.write('<pre>' + JSON.stringify(filtered, 0, 4) + '</pre>');

Using Ramda to retrieve objects from an array by comparing them with each element in a separate array

Answer №1

Answer №2

Answer №3

Answer №4

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