CODEWITHSUNDEEP
javascript
Yerlan Yeszhanov
Yerlan Yeszhanov

Reputation: 2449

How to get unique years from array?

I have an array with date range between three years. How to get unique years from it? I have tried this, but it pushes all items in the new array.

let array = [
  { x: Mon Feb 01 2016 , y:  32 }
  { x: Mon Feb 01 2016 , y:  95 }
  { x: Mon Feb 01 2017 , y: 117 }
  { x: Mon Feb 01 2018 , y:  23 }
  { x: Mon Feb 01 2018 , y:  14 }
]

let sortedArray = []

for (let i = 0; i < array.length; i++) {
  const obj = dates[i]
  sortedArray.push(obj.x.getFullYear())

}

Upvotes: 2

Views: 401

Answers (5)

Sahil Raj Thapa
Sahil Raj Thapa

Reputation: 2483

You can also use combination of map, filter and indexOf

var array = [{ x: 'Mon Feb 01 2016', y:  32 }, { x: 'Mon Feb 01 2016' , y:  95 }, { x: 'Mon Feb 01 2017' , y: 117 }, { x: 'Mon Feb 01 2018' , y:  23 }, { x: 'Mon Feb 01 2018' , y:  14 }]
var unique = array
          .map( yearDate => new Date(yearDate.x).getFullYear())
          .filter( (year, index, arr) => arr.indexOf(year) === index ) 
console.log(unique) // [2016, 2017, 2018]

Upvotes: 0

hygull
hygull

Reputation: 8740

I think you have pasted the code in hurry. Never do that as this allows other developers to understand and answer quickly. I have edited it little bit and made it working as follows.

let array = [
    { x: "Mon Feb 01 2016" , y:  32 },
    { x: "Mon Feb 01 2016" , y:  95 },
    { x: "Mon Feb 01 2017" , y: 117 },
    { x: "Mon Feb 01 2018" , y:  23 },
    { x: "Mon Feb 01 2018" , y:  14 }
];

let sortedArray = [];

for (let i = 0; i < array.length; i++) {
    let obj = array[i];
    let year = (new Date(obj.x)).getFullYear();

    if(!(sortedArray.indexOf(year) > -1)) {
        sortedArray.push(year); // Pushing year which does not exist in array
    }
}

console.log(sortedArray); // [ 2016, 2017, 2018 ]

Upvotes: 1

Nina Scholz
Nina Scholz

Reputation: 386746

You could map the year and get from a Set the unique values.

If necessary add a sorting.

unique.sort((a, b) => a - b); // asc


var array = [{ x: 'Mon Feb 01 2016', y:  32 }, { x: 'Mon Feb 01 2016' , y:  95 }, { x: 'Mon Feb 01 2017' , y: 117 }, { x: 'Mon Feb 01 2018' , y:  23 }, { x: 'Mon Feb 01 2018' , y:  14 }],
    unique = Array.from(new Set(array.map(({ x }) => new Date(x).getFullYear())));

console.log(unique);

Upvotes: 3

Islam ElHakmi
Islam ElHakmi

Reputation: 274

you can do this 

let array=[

{x: 'Mon Feb 01 2016' , y: 32},
{x: 'Mon Feb 01 2016' , y: 95},
{x: 'Mon Feb 01 2017' , y: 117},
{x: 'Mon Feb 01 2018' , y: 23},
{x: 'Mon Feb 01 2018' , y: 14},
];

let sortedArray = [];
let unique = [];
 for (let i = 0; i < array.length; i++) {
  const obj = array[i];
  var date = new Date(obj.x);
  if(!unique[date.getFullYear()]){
   sortedArray.push(date.getFullYear());
   unique[date.getFullYear()] = true;
  }

}

Upvotes: 0

Mr. Polywhirl
Mr. Polywhirl

Reputation: 48693

You can map the items to grab the x field's 4th token (separated by spaces) and throw those values into a set. You can use the spread operator to convert the values into an array and then sort for safe measure.

let array = [
  { x: 'Mon Feb 01 2016' , y:  32 },
  { x: 'Mon Feb 01 2016' , y:  95 },
  { x: 'Mon Feb 01 2017' , y: 117 },
  { x: 'Mon Feb 01 2018' , y:  23 },
  { x: 'Mon Feb 01 2018' , y:  14 }
]
let uniqueYears = [...new Set(array.map(item => item.x.split(' ')[3]))].sort();

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

Upvotes: 1

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