Filter array of objects to get distinct values into new array

Question

I have created a fiddle here of my question, with the help of some of the answers below.

I have an array of objects. An individual object in the a array contains:

obj1, obj2, obj3...

An example of one of the object is:

{
client_id: "85"
id: 1477
organisation_id: 5
task_project_id: 26
project_name: "Reiciendis adipisci fugiat."
project_description: "Soluta consequatur labore et dolores"
task_description: "Qui sunt at aut."
task_end_time: null
task_start_time: "2016-05-21 09:00:00"
transaction_id: null
}

I want to generate a new array of objects from this first array containing distinct entries of task_project_id. The new array should contain distinct objects structured per below:

{
task_project_id: 26
project_name: "Reiciendis adipisci fugiat."
}

I have tried jQuery.grep, array.filter, array.map but to no avail. I also cannot seem to find examples using "extract array of distinct objects" as search. Could someone point me to an example please. Thanks.

I don't get it. How does the first object example relate to the second? And how do you define a "unique" object? — Mitya
– Mitya, Commented Sep 3, 2016 at 21:02

sebnukem · Accepted Answer · 2016-09-04 00:47:42Z

2

array.map should work just fine:

var b = a.map(function(e) {
  return {
    task_project_id: e.task_project_id,
    project_description: e.project_description
  }
});

Edit: filter out duplicates, by storing a list of already encountered "seen" task project ids:

var seen = {}; // keys = list of unique task project ids
var b = a.filter(function (e) {
  return seen[e.task_project_id] ? false : (seen[e.task_project_id] = true);
});

Putting it all together:

var newArray = (function (a) {
  var seen = {};
  return a.filter(function (e) {
    return seen[e.task_project_id] ? false : (seen[e.task_project_id] = true);
  }).map(function (e) {
    return {
      task_project_id: e.task_project_id,
      project_description: e.project_description
    }
  });
})(oldArray);

edited Sep 4, 2016 at 0:47

answered Sep 3, 2016 at 21:09

sebnukem

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1 Comment

TheRealPapa Over a year ago

Hi @sebnukem thanks for the reply. I am looking to filter out duplicate task_project_id entries though.

Nikhilesh Shivarathri · Accepted Answer · 2016-09-03 21:05:35Z

2

Is this what you want ? Check the output.!

var oldArray = [{
    client_id: "85",
    id: 1477,
    organisation_id: 5,
    task_project_id: 26,
    project_name: "Reiciendis adipisci fugiat.",
    project_description: "Soluta consequatur labore et dolores",
    task_description: "Qui sunt at aut.",
    task_end_time: null,
    task_start_time: "2016-05-21 09:00:00",
    transaction_id: null
  }, {
    client_id: "86",
    id: 1434,
    organisation_id: 5,
    task_project_id: 22,
    project_name: "Reiciddgdgdfgci fugiat.",
    project_description: "Soluta consequatur labore et dolores",
    task_description: "Qui sunt at aut.",
    task_end_time: null,
    task_start_time: "2016-05-21 09:00:00",
    transaction_id: null
  }],
  newArray;
newArray = oldArray.map(function(obj) {
  return {
    task_project_id: obj.task_project_id,
    project_description: obj.project_description
  }
});

console.log(newArray);

answered Sep 3, 2016 at 21:05

Nikhilesh Shivarathri

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1 Comment

TheRealPapa Over a year ago

Hi @Nikhilesh Shivarathri close! I am seeking the new array to contain distinct task_project_id entries only. I think I can work from this now though. Thanks for the help!

Jackpile · Accepted Answer · 2016-09-05 16:53:19Z

0

ES6:

let map = new Map();
a = [{a:1, b:"blue"},{a:1, b:"red"}]
a.map(item=>map.set(item.a, item));
let result = [...map.values()];

result:

[ { a: 1, b: 'red' } ]

edited Sep 5, 2016 at 16:53

answered Sep 5, 2016 at 16:41

Jackpile

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