Note: the selected answer is changing the array order which is not preferred, here I provide more different variations that achieving the same result and keeping the array in order
Discussion
given [98.88, .56, .56] how do you want to round it? you have four option
1- round things up and subtract what is added from the rest of the numbers, so the result becomes [98, 1, 1]
this could be a good answer, but what if we have [97.5, .5, .5, .5, .5, .5]? then you need to round it up to [95, 1, 1, 1, 1, 1]
do you see how it goes? if you add more 0-like numbers, you will lose more value from the rest of your numbers. this could be very troublesome when you have a big array of zero-like number like [40, .5, .5 , ... , .5]. when you round up this, you could end up with an array of ones: [1, 1, .... , 1]
so round-up isn't a good option.
2- you round down the numbers. so [98.88, .56, .56] becomes [98, 0, 0], then you are 2 less than 100. you ignore anything that is already 0, then add up the difference to the biggest numbers. so bigger numbers will get more.
3- same as previous, round down numbers, but you sort descending based on the decimals, divide up the diff based on the decimal, so biggest decimal will get the diff.
4- you round up, but you add what you added to the next number. so like a wave what you have added will be redirected to the end of your array. so [98.88, .56, .56] becomes [99, 0, 1]
none of these are ideal, so be mindful that your data is going to lose its shape.
here I provide a code for cases 2 and 3 (as case No.1 is not practical when you have a lot of zero-like numbers). it's modern Js and doesn't need any library to use
2nd case
const v1 = [13.626332, 47.989636, 9.596008, 28.788024];// => [ 14, 48, 9, 29 ]
const v2 = [16.666, 16.666, 16.666, 16.666, 16.666, 16.666] // => [ 17, 17, 17, 17, 16, 16 ]
const v3 = [33.333, 33.333, 33.333] // => [ 34, 33, 33 ]
const v4 = [33.3, 33.3, 33.3, 0.1] // => [ 34, 33, 33, 0 ]
const v5 = [98.88, .56, .56] // =>[ 100, 0, 0 ]
const v6 = [97.5, .5, .5, .5, .5, .5] // => [ 100, 0, 0, 0, 0, 0 ]
const normalizePercentageByNumber = (input) => {
const rounded: number[] = input.map(x => Math.floor(x));
const afterRoundSum = rounded.reduce((pre, curr) => pre + curr, 0);
const countMutableItems = rounded.filter(x => x >=1).length;
const errorRate = 100 - afterRoundSum;
const deductPortion = Math.ceil(errorRate / countMutableItems);
const biggest = [...rounded].sort((a, b) => b - a).slice(0, Math.min(Math.abs(errorRate), countMutableItems));
const result = rounded.map(x => {
const indexOfX = biggest.indexOf(x);
if (indexOfX >= 0) {
x += deductPortion;
console.log(biggest)
biggest.splice(indexOfX, 1);
return x;
}
return x;
});
return result;
}
3rd case
const normalizePercentageByDecimal = (input: number[]) => {
const rounded= input.map((x, i) => ({number: Math.floor(x), decimal: x%1, index: i }));
const decimalSorted= [...rounded].sort((a,b)=> b.decimal-a.decimal);
const sum = rounded.reduce((pre, curr)=> pre + curr.number, 0) ;
const error= 100-sum;
for (let i = 0; i < error; i++) {
const element = decimalSorted[i];
element.number++;
}
const result= [...decimalSorted].sort((a,b)=> a.index-b.index);
return result.map(x=> x.number);
}
4th case
you just need to calculate how much extra air added or deducted to your numbers on each roundup and, add or subtract it again in the next item.
const v1 = [13.626332, 47.989636, 9.596008, 28.788024];// => [14, 48, 10, 28 ]
const v2 = [16.666, 16.666, 16.666, 16.666, 16.666, 16.666] // => [17, 16, 17, 16, 17, 17]
const v3 = [33.333, 33.333, 33.333] // => [33, 34, 33]
const v4 = [33.3, 33.3, 33.3, 0.1] // => [33, 34, 33, 0]
const normalizePercentageByWave= v4.reduce((pre, curr, i, arr) => {
let number = Math.round(curr + pre.decimal);
let total = pre.total + number;
const decimal = curr - number;
if (i == arr.length - 1 && total < 100) {
const diff = 100 - total;
total += diff;
number += diff;
}
return { total, numbers: [...pre.numbers, number], decimal };
}, { total: 0, numbers: [], decimal: 0 });
