CODEWITHSUNDEEP
javascript
FD3
FD3

Reputation: 1956

How to return max number arr with the length of subArr?

Products Array has an array property called subArr and my goal is to return an array with the length of subArr which will include biggest numbers.

Array

const products = [
  {
    name: "car",
    subArr: ["4", "200", "599.4", "4444"]
  },
  {
    name: "tv",
    subArr: ["44477", "50", "579.2", "3232"]
  },
  {
    name: "glass",
    subArr: ["2121.1", "6347", "8867", "90.01"]
  }
];

My desired array is [44477, 4444, 8867, 6347]

I tried to map through the main array and the loop through the second one but can't figure out how to get an array with the length of subArr

const products = [
  {
    name: "car",
    numArr: ["4", "200", "599.4", "4444"]
  },
  {
    name: "tv",
    numArr: ["44477", "50", "579.2", "3232"]
  },
  {
    name: "glass",
    numArr: ["2121.1", "6343", "8867", "90.01"]
  }
];

function getMaxFromArr(products) {
  if (!products.length) {
    return [];
  }
  return products[0].numArr.map((val, index) => {
    return products.map((prod) => parse(prod.numArr[index]));
   
  });
}

const parse = value => parseFloat(value);

const result = getMaxFromArr(products);
console.log("result", result);

Any help will be appreciated

Upvotes: 1

Views: 105

Answers (5)

Nick Parsons
Nick Parsons

Reputation: 50854

Judging by your current code you're trying to "zip" the arrays within your products, but for each "column"/index that you zip, you want to grab the max value. That could be achieved by taking the max of your inner array with Math.max() and spreading (...) the mapped numbers into that. You can remove the parse() method as Math.max() will parse the strings to numbers internally.

See your modified code below (I've also modified it to use optional chaining (?.) and the nullish coalescing (??), but you can keep it to use the same if-statement you had if you wish):

const products = [ { name: "car", subArr: ["4", "200", "599.4", "4444"] }, { name: "tv", subArr: ["44477", "50", "579.2", "3232"] }, { name: "glass", subArr: ["2121.1", "6347", "8867", "90.01"] } ];

function getMaxFromArr(products) {
  return products[0]?.subArr.map((val, index) =>
    Math.max(...products.map((prod) => prod.subArr[index]))
  ) ?? [];
}

const result = getMaxFromArr(products);
console.log("result", result);

Upvotes: 1

Gass
Gass

Reputation: 9384

I tried not to modify to much your code. You can read the logic in the comments:

  1. Get the length of first numArr
  2. Convert all strings in all numArr props to numbers and save them in a new array
  3. Sort and slice

const products = [
  {
    name: "car",
    numArr: ["4", "200", "599.4", "4444"]
  },
  {
    name: "tv",
    numArr: ["44477", "50", "579.2", "3232"]
  },
  {
    name: "glass",
    numArr: ["2121.1", "6343", "8867", "90.01"]
  }
];

function getMaxFromArr(products) {
  let allNumbers = []
  
  if (!products.length) {
    return []
  }
  else{
    // get the length of first numArr
    let subArrLength = products[0].numArr.length
    
    // convert all strings in all numArr props to numbers and save them in a new array
    products.forEach((prod) => {
      prod.numArr.forEach((n) => allNumbers.push(Number(n)))
    })
    
    // sort and slice
    console.log(allNumbers.sort((a,b) => a - b).slice(allNumbers.length - subArrLength))
  }
}

getMaxFromArr(products)

Upvotes: 0

Asraf
Asraf

Reputation: 1369

Approach:

  1. First merge the all subArrs by reduce()
  2. Convert them to numbers using .map(Number)
  3. Sort the newArray and finally slice() them.

const products = [ { name: "car", subArr: ["4", "200", "599.4", "4444"] }, { name: "tv", subArr: ["44477", "50", "579.2", "3232"] }, { name: "glass", subArr: ["2121.1", "6347", "8867", "90.01"] } ];
const sortNum = (a, b) => b - a; //descending order
const findMaxArr = (arr, sArrSize) => products.reduce((a, {subArr}) => [...a, ...subArr.map(Number)],[]).sort(sortNum).slice(0, sArrSize);
console.log(findMaxArr(products, products[0].subArr.length));

Upvotes: 3

Peter Lam
Peter Lam

Reputation: 1

const products = [{
    name: "car",
    numArr: ["4", "200", "599.4", "4444"]
  },
  {
    name: "tv",
    numArr: ["44477", "50", "579.2", "3232"]
  },
  {
    name: "glass",
    numArr: ["2121.1", "6343", "8867", "90.01"]
  }
];

function getMaxFromArr(products) {
  var BiggestNum = 0;
  var BiggestNumArray = [];
  if (!products.length) {
    return [];
  }
  products.map((value, index) => {
    var Array = value.numArr;
    for (let i = 0; i < Array.length; i++) {
      if (BiggestNum < Number(Array[i])) {
        BiggestNum = Number(Array[i])
        BiggestNumArray = Array
      }
    }

  })
  return BiggestNumArray

}

const parse = value => parseFloat(value);

const result = getMaxFromArr(products);
console.log("result", result);

Upvotes: 0

adiga
adiga

Reputation: 35253

  • Get all the numbers to a single array using flatMap and convert them to numbers using Number
  • sort the array of numbers in descending order
  • take the top n items using slice

const products = [{name:"car",numArr:["4","200","599.4","4444"]},{name:"tv",numArr:["44477","50","579.2","3232"]},{name:"glass",numArr:["2121.1","6343","8867","90.01"]}],
      
      topN = products
                .flatMap(p => p.numArr.map(Number))
                .sort((a, b) => b - a)
                .slice(0, products[0].numArr.length)

console.log(topN)

Upvotes: 1

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