javascript reduce find max in array of arrays

Question

I want to find the max number among the first and second elements of each array inside the array of arrays separately:

function largestOfElements(mainArray) {
  return mainArray.map(function(subArray) {
    return subArray.reduce(function(previousLargestNumber, currentLargestNumber) {
      return (currentLargestNumber > previousLargestNumber) ? currentLargestNumber : previousLargestNumber;
    }, 0);
  });
}
console.log(largestOfElements([
  [],
  [13, 47],
  [38, 35],
  [24, 34]
]));

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

the current way returns an array of the largest numbers in each array. How can I return the largest of the first elements and the largest of the second elements? the expected result will be:

[38, 47]

Ele · Accepted Answer · 2018-03-15 01:51:23Z

2

You can use the function reduce.

The initial value for the function reduce are the min values to start getting the highest values.
Check for the length of the current array.
Use destructuring assignment to get the first and second value [first, second].
Check the current value against first and second respectively to get the highest.

var array = [
  [],
  [13, 47],
  [38, 35],
  [24, 34]
];

var result = Object.values(array.reduce((a, c) => {
  if (c.length) {
    var [first, second] = c;
    if (first > a.f) a.f = first;
    if (second > a.s) a.s = second;
  }
  
  return a;
}, {f: Number.MIN_VALUE, s: Number.MIN_VALUE}));

console.log(result);

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

edited Mar 15, 2018 at 1:51

answered Mar 15, 2018 at 1:41

Ele

33.8k7 gold badges43 silver badges80 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

moaningalways Over a year ago

could you add more explanation please?

Giulio · Accepted Answer · 2022-12-14 12:23:44Z

0

var array = [
  [],
  [13, 47],
  [38, 35],
  [24, 34]
];

console.log([0,1].map(i => Math.max(...array.map(v => v[i]).filter(v => v))));

answered Dec 14, 2022 at 12:23

Giulio

5626 silver badges19 bronze badges

Collectives™ on Stack Overflow

javascript reduce find max in array of arrays

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related