CODEWITHSUNDEEP
javascriptarraysalgorithm
kevin ortiz
kevin ortiz

Reputation: 25

compare 2 arrays and check the positions

I have 2 arrays, one has 10 elements and the other one 3, I need to create a new array with the same size of the biggest vector, with a boolean checking true in the position where exist some element from the array of 3 elements

I have the following arrays

array1 = [1,2,3,4,5,6,7,8,9,10]
array2 = [4,6,10]

I tried making 2 for loops

for(var i=0; i<array1.lenght; i++){
    for(var j=0; i<array2.lenght; i++){
      if(array1[i]==array2[j]){
          array3.push(true)
      }else{
          array3.push(false)
      }
    }
}

the vector that I need would be

array3 = [false, false, false, true, false, true, false, false, false, true]

Upvotes: 0

Views: 1022

Answers (5)

Manishkumar Bhavnani
Manishkumar Bhavnani

Reputation: 57

const array1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const array2 = [4, 6, 10];
const finalArray = [];

for (let data of array1) {
    finalArray.push(array2.includes(data));
}

Upvotes: 0

dganenco
dganenco

Reputation: 1616

I would suggest to keep things simple and to use Array#indexOf method to determine if array contains another element.

const array1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const array2 = [4, 6, 10];

const b = array1.map(el => {
  return array2.indexOf(el) !== -1;
});

console.log(b);

Upvotes: 0

Akrion
Akrion

Reputation: 18525

You can also instead of another array use a Set and then Array.map the first away checking if the value is in the Set:

let array1 = [1,2,3,4,5,6,7,8,9,10],
    set = new Set([4,6,10])

let result = array1.map(x => set.has(x))

console.log(result)

Upvotes: 1

Jack Bashford
Jack Bashford

Reputation: 44125

Use map like so with shift like so:

const array1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const array2 = [4, 6, 10];
const array3 = array1.map(e => {
  if (array2[0] == e) {
    array2.shift();
    return true;
  } 
  return false;
});
console.log(array3);
.as-console-wrapper { max-height: 100% !important; top: auto; }

If you just want a basic check as for whether the element is in the array, not the order, then use includes.

const array1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const array2 = [4, 6, 10];
const array3 = array1.map(e => array2.includes(e));
console.log(array3);
.as-console-wrapper { max-height: 100% !important; top: auto; }

Upvotes: 2

Hien Nguyen
Hien Nguyen

Reputation: 18975

You can forEach first array and use include method to check if item existed in array as

let array1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
let array2 = [4, 6, 10];
let array3 = [];
array1.forEach(function (c) {
	if (array2.includes(c)) {
		array3.push(true)
	} else {
		array3.push(false);
	}
})

console.log(array3)

Upvotes: 2

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