Let's say I have four arrays:
var arr1 = [117, 121, 18, 24];
var arr2 = [132, 19, 432, 23];
var arr3 = [32, 23, 137, 145];
var arr4 = [900, 332, 23, 19];
I need to create a new array from these, arr5, where key 1 is the highest number from key 1 of arr1, arr2, arr3, arr4, and the same for key 2, 3, etc. So I would have arr5 as:
[900, 332, 432, 145]
What would be the simplest way of accomplishing this?
Please no jQuery, just plain vanilla JS.
Solution using simple for-loop and Math.max(). Assuming that your arrays have the same length:
var arr5 = [];
for (var i = 0; i < arr1.length; i++) {
arr5.push(Math.max(arr1[i], arr2[i], arr3[i], arr4[i]));
}
There are multiple ways of accomplishing this.
One would be using Math.max (https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Global_Objects/Math/max)
While using the spread operator (https://developer.mozilla.org/de/docs/Web/JavaScript/Reference/Operators/Spread_operator) you can do it like this:
arr5.push( Math.max(...arr1) );
arr5.push( Math.max(...arr2) );
// etc..
Maybe try yourself how to accomplish this with a dynamic input of arrays, maybe a little wrapping function for the Math.max call, where you pass all arrays you like and which returns an array with only the max values.
Hope it helps.
This is a proposal with two nested Array#forEach.
var arr1 = [117, 121, 18, 24],
arr2 = [132, 19, 432, 23],
arr3 = [32, 23, 137, 145],
arr4 = [900, 332, 23, 19],
result = function (array) {
var r = [];
array.forEach(function (a) {
a.forEach(function (b, i) {
if (!( r[i] > b)) {
r[i] = b;
}
});
});
return r;
}([arr1, arr2, arr3, arr4]);
document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');have a look at this solution
var arr1 = [117, 121, 18, 24];
var arr2 = [132, 19, 432, 23];
var arr3 = [32, 23, 137, 145];
var arr4 = [900, 332, 23, 19];
var arr5 = [];
Array.prototype.max = function() {
return Math.max.apply(null, this);
};
for(var i=0; i<4; i++){
var arr=[arr1[i], arr2[i], arr3[i], arr4[i]];
var max = Math.max.apply(null, arr);
arr5.push(max);
}
console.log(arr5);
I think that you should use madox2's solution!
That said – one way to tackle about your problem is to let your arrays form a matrix, transpose that matrix, and map Math.max over the resulting rows.
Something like this:
function transpose(m) {
return m[0].map(function(_, i) {
return m.map(function(arr) {
return arr[i];
});
});
}
var arr5 = transpose([arr1, arr2, arr3, arr4]).map(function(e) {
return Math.max.apply(null, e);
});
