Javascript | remove unwanted data from array of object

Question

I just want first year and last year element from Array Object

example this is the data ( it is sorted so I just don't wanna messed that up) :

[
  { make: 'audi', model: 'rs5', year: '2013' },
  { make: 'audi', model: 'rs5', year: '2015' },
  { make: 'audi', model: 'r8', year: '2020' },
  { make: 'ford', model: 'mustang', year: '2012' },
  { make: 'ford', model: 'fusion', year: '2015' },
  { make: 'ford', model: 'mustang', year: '2033' },
  { make: 'kia', model: 'optima', year: '2010' },
  { make: 'kia', model: 'optima', year: '2012' },
  { make: 'kia', model: 'optima', year: '2020' },
  { make: 'kia', model: 'optima', year: '2030' },
  { make: 'kia', model: 'optima', year: '2040' }
]

and I want it like this all the middle years removed :

[
  { make: 'audi', model: 'rs5', year: '2013' },
  { make: 'audi', model: 'r8', year: '2020' },
  { make: 'ford', model: 'mustang', year: '2012' },
  { make: 'ford', model: 'mustang', year: '2033' },
  { make: 'kia', model: 'optima', year: '2010' },
  { make: 'kia', model: 'optima', year: '2040' }
]

Why not sort it by the years first, then by make? You could then just separate the array by make, and then grab the first and last values. — Kobe
– Kobe, Commented Jan 23, 2020 at 11:50
@NinaScholz I'm assuming they're getting the latest and oldest by make, not model — Kobe
– Kobe, Commented Jan 23, 2020 at 11:56

Kobe · Accepted Answer · 2020-01-23 13:18:07Z

3

You could just separate the array by make, and then grab the first and last values of each make:

const arr = [
  { make: 'audi', model: 'rs5', year: '2013' },
  { make: 'audi', model: 'rs5', year: '2015' },
  { make: 'audi', model: 'r8', year: '2020' },
  { make: 'ford', model: 'mustang', year: '2012' },
  { make: 'ford', model: 'fusion', year: '2015' },
  { make: 'ford', model: 'mustang', year: '2033' },
  { make: 'kia', model: 'optima', year: '2010' },
  { make: 'kia', model: 'optima', year: '2012' },
  { make: 'kia', model: 'optima', year: '2020' },
  { make: 'kia', model: 'optima', year: '2030' },
  { make: 'kia', model: 'optima', year: '2040' }
]

const grouped = arr.reduce((a, el) => (a[el.make] ? a[el.make].push(el) : a[el.make] = [el], a), {})
const out = Object.values(grouped).reduce((a, group) => (a.push(group[0], group[group.length - 1]), a), [])

console.log(out)

edited Jan 23, 2020 at 13:18

answered Jan 23, 2020 at 11:57

Kobe

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3 Comments

Kobe Over a year ago

OP hasn't specified how to handle that case, I'm not sure which one they would want to pick. Unless I've missed something...

SRTechConnect Over a year ago

Thanks Kobe it really helped me a lot.

Kobe Over a year ago

@SRTechConnect No problem, if you need more help, feel free to ask :)

Nina Scholz · Accepted Answer · 2020-01-23 12:06:50Z

You could reduce the array by looking for the next to last item and if it has the same make as the actual object, then update the last index.

Otherwise push the object to the result set.

This approach uses the sorted array by make and year.

var data = [{ make: 'audi', model: 'rs5', year: '2013' }, { make: 'audi', model: 'rs5', year: '2015' }, { make: 'audi', model: 'r8', year: '2020' }, { make: 'ford', model: 'mustang', year: '2012' }, { make: 'ford', model: 'fusion', year: '2015' }, { make: 'ford', model: 'mustang', year: '2033' }, { make: 'kia', model: 'optima', year: '2010' }, { make: 'kia', model: 'optima', year: '2012' }, { make: 'kia', model: 'optima', year: '2020' }, { make: 'kia', model: 'optima', year: '2030' }, { make: 'kia', model: 'optima', year: '2040' }],
    result = data.reduce((r, o) => {
        if ((r[r.length - 2] || {}).make === o.make) r[r.length - 1] = o; 
        else r.push(o);
        return r;
    }, []);

console.log(result);

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

Rabby · Accepted Answer · 2020-01-24 06:06:48Z

0

If your array is sorted then try this

var newcar = [];
var myvar = [];
for (var i=0; i<(car.length)-1; i++) {
    if(car[i].make == car[i+1].make) 
    {
        myvar.push(car[i]);
        if(i+1 == car.length-1)
        {
            myvar.push(car[i+1]);
            newcar.push(myvar[0]);
            var lastitem = myvar.pop();
            newcar.push(lastitem);
        }
    }
    else
    {
        myvar.push(car[i]);
        newcar.push(myvar[0]);
        var lastitem = myvar.pop();
        newcar.push(lastitem);
        myvar = [];
    }
}

answered Jan 24, 2020 at 6:06

Rabby

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Comments

Mohammad Al Kalaleeb · Accepted Answer · 2020-01-23 13:11:30Z

-1

use filter method on the array, you can find docs in the following https://www.geeksforgeeks.org/es6-array-filter-method/ and

example:

const arr = [1,2,3,4,5];
console.log(arr.filter((i) => {
// A Condition, if true it's displayed if not it's discarded
return i > 2;
}));

answered Jan 23, 2020 at 13:11

Mohammad Al Kalaleeb

163 bronze badges

Comments

Axel Köhler · Accepted Answer · 2020-01-23 11:59:50Z

You can loop through the array and save the ones with the maximum and minimum year like this:

let data = [
  { make: 'audi', model: 'rs5', year: '2013' },
  { make: 'audi', model: 'rs5', year: '2015' },
  { make: 'audi', model: 'r8', year: '2020' },
  { make: 'ford', model: 'mustang', year: '2012' },
  { make: 'ford', model: 'fusion', year: '2015' },
  { make: 'ford', model: 'mustang', year: '2033' },
  { make: 'kia', model: 'optima', year: '2010' },
  { make: 'kia', model: 'optima', year: '2012' },
  { make: 'kia', model: 'optima', year: '2020' },
  { make: 'kia', model: 'optima', year: '2030' },
  { make: 'kia', model: 'optima', year: '2040' }
];

let a = {};

for(let i = 0; i<data.length; i++) {
  if( !a[data[i].make] ) {
    a[data[i].make] = {};
  }
  if( !a[data[i].make].max || a[data[i].make].max.year < data[i].year ) {
    a[data[i].make].max = data[i];
  }
  if( !a[data[i].make].min || a[data[i].make].min.year > data[i].year ) {
    a[data[i].make].min = data[i];
  }
}

let output = [];

Object.keys(a).forEach(make => {
  output.push( a[make].min );
  output.push( a[make].max );
});

console.dir( output );

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