Handle Array of Object manipulation

Question

Below I have an array of objects

var data = [{
  "time": "1572024707.4763825",
  "rssi": "32",
  "id": "77777"
}, {
  "time": "1572024709.0991757",
  "rssi": "32",
  "id": "77777"
}, {
  "time": "1572024704.4570136",
  "rssi": "32",
  "id": "555555"
}, {
  "time": "1572024708.3903246",
  "rssi": "32",
  "id": "77777"
}, {
  "time": "1572024699.7132683",
  "rssi": "32",
  "id": "66666"
}]

How can I restructure it to remove the repeating id's with the oldest time

I tried to pull all the unique IDs from the array so I can loop through the data array but then the code started to get too long.

  data.forEach(item => {

    IDs.push(item.id);
  });

  var unqIDs = [...new Set(IDs)];
  console.log(unqIDs);

the output should look like this

outPutShouldBe = [{
  "time": "1572024699.7132683",
  "rssi": "32",
  "id": "66666"
},{
  "time": "1572024709.0991757",
  "rssi": "32",
  "id": "77777"
},  {"time": "1572024704.4570136",
  "rssi": "32",
  "id": "555555"
}
]

What does "the code started to get too long" mean? – Scott Hunter Oct 25 '19 at 18:06 — Scott Hunter, Oct 25 '19 at 18:06

Willman.Codes · Answer 1 · 2019-10-25T18:37:21.170

Using forEach() find() filter() and filter() to decide which element to return

var data = [{"time": "1572024707.4763825","rssi": "32","id": "77777"},{"time": "1572024709.0991757","rssi": "32","id": "77777"}, {"time": "1572024704.4570136","rssi": "32","id": "555555"}, {"time": "1572024708.3903246","rssi": "32","id": "77777"}, {"time": "1572024699.7132683","rssi": "32","id": "66666"}]

let resultsArray = []

data.forEach(obj=>{
  const foundObj = resultsArray.find(data => data.id === obj.id)

  if(foundObj && new Date(foundObj.time) > new Date(obj.time)){
     const filteredArray = resultsArray.filter(data => data.id === obj.id)
     resultsArray = [...filteredArray , foundObj]
  } else if (!foundObj){
     resultsArray.push(obj)
  }
})

console.log(resultsArray)

I'll study this one in more detail later, but it did not work for me — Jay, Oct 25 '19 at 18:27

Scott Hunter · Accepted Answer · 2019-10-25T23:55:15.947

4

Create an object mapping ids to the item w/ the earliest time of those with that id:

var keydata = {};
data.forEach(item=>{ 
    var p = keydata[item.id]; 
    if ( !p || p.time>item.time ) { 
        keydata[item.id] = item; 
    }});

Now gather up the values in that object:

var newdata = [];
for ( var k in keydata ) { 
    newdata.push(keydata[k]);
}

or the more elegant (thanks, @TulioF.):

var newdata = Object.values(keydata)

edited Oct 25 '19 at 23:55

answered Oct 25 '19 at 18:17

Scott Hunter

48,888
12
60
101

For your second step, you could do `Object.values(keydata)` to get the dictionary values. – Tolio Oct 25 '19 at 20:14

score 2 · Answer 3 · answered Oct 25 '19 at 18:33

You coud take an object as hash table and get the values directly.

var data = [{ time: "1572024707.4763825", rssi: "32", id: "77777" }, { time: "1572024709.0991757", rssi: "32", id: "77777" }, { time: "1572024704.4570136", rssi: "32", id: "555555" }, { time: "1572024708.3903246", rssi: "32", id: "77777" }, { time: "1572024699.7132683", rssi: "32", id: "66666" }],
    result = Object.values(data.reduce((r, o) => {
        if (!r[o.id] || +r[o.id].time > +o.time) r[o.id] = o;
        return r;
    }, {}));

console.log(result)

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Shubham Verma · Answer 4 · 2019-10-25T19:49:01.277

0

Here you can do something like this :

let existMap = {};
data.filter(val => {
  if((val.id in existMap) && (val.time>existMap[val.id])) return;
  else{
    existMap[val.id] = val.time;
    return true;
  }
})
console.log(result)

The condition can be changed based on requirement. just want to reference for your problem.

edited Oct 25 '19 at 19:49

answered Oct 25 '19 at 18:10

Shubham Verma

4,918
1
9
22

How does this "remove the repeating id's with the oldest time"? – Scott Hunter Oct 25 '19 at 18:25
Updated my code. The condition can change based on the requirement – Shubham Verma Oct 25 '19 at 19:49

blueseal · Answer 5 · 2019-10-25T18:47:35.893

use lodash to sort the array in descending order or ascending order as per your need (desc, asc) and get the zeroth object. try something like this. filter and orderBy

var data = [{
  "time": "1572024707.4763825",
  "rssi": "32",
  "id": "77777"
}, ....];

let idsSet = new Set();

data.map(item=> idsSet.add(item.id));

let idsArr = Array.from(idsSet);

let newArr = [];
idsArr.map(id=>{
let tempArray = data.filter(item => item.id === id);
return newArr.push((_.orderBy(tempArray, ['time'],['desc']))[0]);
} )

console.log(newArr);

console output

[ {
  "time": "1572024709.0991757",
  "rssi": "32",
  "id": "77777"
}, {
  "time": "1572024704.4570136",
  "rssi": "32",
  "id": "555555"
},  {
  "time": "1572024699.7132683",
  "rssi": "32",
  "id": "66666"
}];

Handle Array of Object manipulation

the output should look like this

5 Answers5