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javascriptarrays
Valera Checha
Valera Checha

Reputation: 294

filter array by equal values

I have an array : 

let array = ['yay', 'yay', 'yay', 'opps', 'yay', 'yay', 'opps', 'opps', 'opps'];

How can I filter this array if in result I need it: 

let filterArray = [['yay', 3] ['opps', 1], ['yay', 2], ['opps' 3]];

Thank you.

Upvotes: 1

Views: 6306

Answers (7)

Madmadi
Madmadi

Reputation: 2140

You can use this:

let filterArray = array.reduce((acc, item) => {
    let similarItemIndex = acc.findIndex(i => i[0] === item);

    if (similarItemIndex > -1) {
        acc.push([item, 1]);
    } else {
        acc[similarItemIndex] = [item, acc[similarItemIndex][0] + 1];
    }

    return acc;
}, []);

Upvotes: 0

gurvinder372
gurvinder372

Reputation: 68393

Use reduce

arr.reduce( (a,c) => {
   var lastValue = (a[a.length - 1] || [])[0]; //find last item in accumulator a
   c == lastValue ? a[a.length - 1][1]++ : a.push([c,1]); //if last value is same then increase count, else add new item
   return a; 
} ,[]) //initialize accumulator a to empty array

Demo

var arr = ['yay', 'yay', 'yay', 'opps', 'yay', 'yay', 'opps', 'opps', 'opps'];

var output = arr.reduce( (a,c) => {
   var lastValue = (a[a.length - 1] || [])[0];
   c == lastValue ? a[a.length - 1][1]++ : a.push([c,1]);
   return a; 
} ,[]);
console.log( output );

Upvotes: 2

Felipe Plazas
Felipe Plazas

Reputation: 334

Yet another solution:

let array = ['yay', 'yay', 'yay', 'opps', 'yay', 'yay', 'opps', 'opps', 'opps'];
let rs = {};
array.forEach((w) => rs[w] == undefined ? rs[w] = 1 : rs[w] += 1);
let result = Object.keys(rs).map((key) => [key, rs[key]]);
console.log(result);

Upvotes: 0

Hassan Imam
Hassan Imam

Reputation: 22534

You can use array#reduce to group similar words in an array and for repeating word increment its count.

let array = ['yay', 'yay', 'yay', 'opps', 'yay', 'yay', 'opps', 'opps', 'opps'],
    result = array.reduce((r,word,i,a) => {
      word == a[i-1] ? r[r.length - 1][1]++ : r.push([word, 1]);
      return r;
    },[]);
console.log(result);

Upvotes: 0

Anurag Singh Bisht
Anurag Singh Bisht

Reputation: 2753

You can use Array.reduce method to iterate through your original array and create the new array.

  • If acc (accumulated array) is empty push the [curr, 1] (current variable and count) in the array
  • If acc (accumulated array) last pushed index contains the curr variable, then update the count
  • If acc (accumulated array) last pushed index does not contains the curr variable, then push the [curr, 1] in acc.

let array = ['yay', 'yay', 'yay', 'opps', 'yay', 'yay', 'opps', 'opps', 'opps'];

let modifiedArray = array.reduce((acc, curr) => {
  if (!acc.length) {
    acc.push([curr, 1]);
  } else {
    let lastPushedArray = acc[acc.length-1];
    if (lastPushedArray[0] === curr) {
      acc[acc.length-1][1]++;
    } else {
      acc.push([curr, 1]);
    }
  }
  return acc;
}, []);

console.log(modifiedArray);

Upvotes: 5

Nina Scholz
Nina Scholz

Reputation: 386578

You could reduce the array by checking the last element of the temporary result set.

var array = ['yay', 'yay', 'yay', 'opps', 'yay', 'yay', 'opps', 'opps', 'opps'],
    result = array.reduce((r, v) => {
        var last = r[r.length - 1];
        if (last && last[0] === v) {
            last[1]++;
        } else {
            r.push([v, 1]);
        }
        return r;
    }, []);
    
console.log(result);
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 2

Harsha W
Harsha W

Reputation: 3366

Try the below code. This will not give you the exact output. But you can follow the below method to generate desired output.

var array = ['yay', 'yay', 'yay', 'opps', 'yay', 'yay', 'opps', 'opps', 'opps'];
var newArray = {};
array.map( function (a) { if (a in newArray) newArray[a] ++; else newArray[a] = 1; } );
console.log(newArray);

Output

{ yay: 5, opps: 3 }

Upvotes: 0

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