'Find the Max and Min element out of all the nested arrays in javascript
I have a array like so:
var arr = [[12,45,75], [54,45,2],[23,54,75,2]];
I want to find out the largest element and the smallest element out of all the elements in the nested array:
The min should be: 2
and
Max should be 75
I tried the functions below but they do not work:
function Max(arrs)
{
if (!arrs || !arrs.length) return undefined;
let max = Math.max.apply(window, arrs[0]), m,
f = function(v){ return !isNaN(v); };
for (let i = 1, l = arrs.length; i<l; i++) {
if ((m = Math.max.apply(window, arrs[i].filter(f)))>max) max=m;
}
return max;
}
function Min(arrs)
{
if (!arrs || !arrs.length) return undefined;
let min = Math.min.apply(window, arrs[0]), m,
f = function(v){ return !isNaN(v); };
for (let i = 1, l = arrs.length; i<l; i++) {
if ((m = Math.min.apply(window, arrs[i].filter(f)))>min) min=m;
}
return min;
}
It gives out Max as 75 and min as 12.
Any guidance will be appreciated.
Also tried other answers in SO but none help.
The answer at Merge/flatten an array of arrays in JavaScript? resolves the problem of merging arrays.
Whereas my problem is to keep the array as is and perform operations.
Solution 1:[1]
Assuming ES6
const arr = [[12,45,75], [54,45,2],[23,54,75,2]];
const max = Math.max(...[].concat(...arr));
const min = Math.min(...[].concat(...arr));
console.log(max);
console.log(min);Solution 2:[2]
You can flatten the array first (advantage - will work for nested arrays at multiple levels)
var flattenedArr = [[12,45,75], [54,45,2],[23,54,75,2] ].toString().split(",").map(Number);
Then get the min and max from the flattened array
var max = Math.max.apply( null, flattenedArr );
var min = Math.min.apply( null, flattenedArr );
Demo
var flattenedArr = [
[12, 45, 75],
[54, 45, 2],
[23, 54, 75, 2]
].toString().split(",").map(Number);
var max = Math.max.apply(null, flattenedArr);
var min = Math.min.apply(null, flattenedArr);
console.log(max, min);Solution 3:[3]
A ES5 recursive approach by checking the type. It works for deep nested arrays.
var array = [[12, 45, 75], [54, 45, 2], [23, 54, 75, 2]],
min = array.reduce(function min(a, b) {
return Math.min(Array.isArray(a) ? a.reduce(min) : a, Array.isArray(b) ? b.reduce(min) : b);
}),
max = array.reduce(function max(a, b) {
return Math.max(Array.isArray(a) ? a.reduce(max) : a, Array.isArray(b) ? b.reduce(max) : b);
});
console.log(min, max);With functions for using as callback.
function flat(f, v) { return Array.isArray(v) ? v.reduce(f) : v; }
function getMin(a, b) { return Math.min(flat(getMin, a), flat(getMin, b)); }
function getMax(a, b) { return Math.max(flat(getMax, a), flat(getMax, b)); }
var array = [[12, 45, 75], [54, 45, 2], [23, 54, 75, 2]],
min = array.reduce(getMin),
max = array.reduce(getMax);
console.log(min, max);Solution 4:[4]
You can simply merged all the nested array into a single array and then find minimum and maximum value by using Math.min.apply(null, array) and Math.max.apply(null, array)
var arr = [[12,45,75], [54,45,2],[23,54,75,2]];
var merged = [].concat.apply([], arr);
var max = Math.max.apply(null, merged);
var min = Math.min.apply(null, merged);
console.log(max,min)Solution 5:[5]
Solution without concatenation, which works for any level of nesting
let arr = [[12,45,75], [54,45,2],[23,54,75,2]];
function findMaxFromNestedArray(arr) {
let max = Number.MIN_SAFE_INTEGER;
for (let item of arr) {
if(Array.isArray(item)) {
let maxInChildArray = findMaxFromNestedArray(item);
if (maxInChildArray > max) {
max = maxInChildArray;
}
} else {
if (item > max) {
max = item;
}
}
}
return max;
}
console.log(findMaxFromNestedArray(arr))Solution 6:[6]
Solution with only one reduce:
const getMaxMin = (flattened) => {
return flattened.reduce(
(a, b) => {
return {
maxVal: Math.max(b, a.maxVal),
minVal: Math.min(b, a.minVal),
};
},
{
maxVal: -Infinity,
minVal: Infinity,
}
);
}
const flatSingle = arr => [].concat(...arr)
const maxMin = getMaxMin(flatSingle(arr))
console.log(maxMin);
Solution 7:[7]
We can flatten the array with Array.prototype.flat.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/flat
const nestedArray = [[12,45,75], [54,45,2],[23,54,75,2]]
const flattenedArray = nestedArray.flat(2)
const minValue = Math.min.apply(null, flattenedArray)
const maxValue = Math.max.apply(null, flattenedArray)
console.log( {flattenedArray, minValue, maxValue} )Solution 8:[8]
A different solution
var arry=[[12,45,75], [54,45,2],[23,54,75,2]];
console.log("MAX",Math.max(...arry.join().split(',').map(e=>+e)));
console.log("MIN",Math.min(...arry.join().split(',').map(e=>+e)));Solution 9:[9]
const getFlatArr = (arr) => arr.join().split(',').map(Number)
const getMax = (arr) => {
const newArr = getFlatArr(arr)
let max = newArr[0]
newArr.forEach((value) => {
max = value > max ? value : max
})
return max
}
const getMin = (arr) => {
const newArr = getFlatArr(arr)
let min = newArr[0]
newArr.forEach((value) => {
min = value < min ? value : min
})
return min
}
const arr1 = [
[12, 45, 75],
[54, 45, 2],
[23, 54, 75, 2],
]
console.log(`Max: ${getMax(arr1)}`)
console.log(`Min: ${getMin(arr1)}`)
const arr2 = [1, 2, [14, 56, 34, [48, 98]], [14, 16, 11, [18, 81]], 34, 35]
console.log(`Max: ${getMax(arr2)}`)
console.log(`Min: ${getMin(arr2)}`)Solution 10:[10]
I'm just gonna update this with 3 simple approaches:
Assume you have a nested array:
let numbers = [12, 44, [33, 94, 10444], 104]
Your first step is to flatten the array. There are many ways to do this, but specifically 2 of the most simple ways:
const flat = numbers.flat() // 12, 44, 33, 94, 10444, 104
const flat = [].concat(...numbers) // 12, 44, 33, 94, 10444, 104
Then comes the easy part - determining the min/max of the flattened array:
const min = Math.min(...flat) // 12
const max = Math.max(...flat) // 10444
Alternatively, you can sort the flattened array and get the first and last elements:
flat.sort((a,b) => {return a-b}) // 12, 33, 44, 94, 104, 10444
const min = flat.shift() // 12
const max = flat.pop() // 104444
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow