CODEWITHSUNDEEP
javascriptarraysreduce
Bishrul hafi
Bishrul hafi

Reputation: 65

Javascript check the closest different from two array of numbers

I have two arrays of numbers a and b, I want to find closest pair of numbers from this array. But I am stuck inside the reducer, with given match to.

Expected output is 

[
  {
    "dif": 1,
    "val": 3,
    "to": 4
  },
  {
    "dif": 2,
    "val": 3,
    "to": 5
  },
  {
    "dif": 2,
    "val": 8,
    "to": 6
  }
]


const a = [1,2,3,8]
, b = [4,5,6]

const result = b.map(to => {
	return a
  	.map(v => {return {val:v}})
  	.reduce((prev, curr) => {
  	  return Math.abs(curr.val - to) < Math.abs(prev.val - to) ? {dif:Math.abs(prev.val - to), val:curr.val, to} : {dif: Math.abs(prev.val - to), val:prev.val, to}
    });
})

console.log(result)

Upvotes: 0

Views: 94

Answers (3)

Nina Scholz
Nina Scholz

Reputation: 386520

You could generate the cartesian product and sort by difference.

var a = [1, 2, 3, 8],
    b = [4, 5, 6],
    result = a
        .reduce((r, c) => r.concat(b.map(d => ({ dif: Math.abs(c - d), val: c, to: d }))), [])
        .sort((a, b) => a.dif - b.dif);

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

Upvotes: 0

xianshenglu
xianshenglu

Reputation: 5309

another choice:

const a = [1, 2, 3, 8],
    b = [4, 5, 6];
const result = b.map(v => {
    return a.reduce((re, value) => {
        let updateRule = re.val === undefined || (re.val !== undefined && Math.abs(value - re.to)) < re.dif;
        return updateRule ? { val: value, dif: Math.abs(value - re.to), to: v } : re;
    }, { to: v });
});

console.log(result);

Upvotes: 0

curlyBraces
curlyBraces

Reputation: 1105

There is one correction in your code. {dif:Math.abs(prev - to), val:curr.val, to} should be {dif:Math.abs(curr.val - to), val:curr.val, to}

const a = [1,2,3,8]
, b = [4,5,6]

const result = b.map(to => {
	return a
  	.map(v => {return {val:v}})
  	.reduce((prev, curr) => {
  	  return Math.abs(curr.val - to) < Math.abs(prev.val - to) ? {dif:Math.abs(curr.val - to), val:curr.val, to} : {dif: Math.abs(prev.val - to), val:prev.val, to}
    });
})

console.log(result)

Upvotes: 1

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