discourse/plugins/poll/assets/javascripts/lib/even-round.js.es6

29 lines
1009 B
JavaScript

// works as described on http://stackoverflow.com/a/13483710
function sumsUpTo100(percentages) {
return percentages.map(p => Math.floor(p)).reduce((a, b) => a + b) === 100;
}
export default function(percentages) {
var decimals = percentages.map(a => a % 1);
const sumOfDecimals = Math.ceil(decimals.reduce((a, b) => a + b));
// compensate error by adding 1 to n items with the greatest decimal part
for (let i = 0, max = decimals.length; i < sumOfDecimals && i < max; i++) {
// find the greatest item in the decimals array, set it to 0,
// and increase the corresponding item in the percentages array by 1
let greatest = 0;
let index = 0;
for (let j = 0; j < decimals.length; j++) {
if (decimals[j] > greatest) {
index = j;
greatest = decimals[j];
}
}
++percentages[index];
decimals[index] = 0;
// quit early when there is a rounding issue
if (sumsUpTo100(percentages)) break;
}
return percentages.map(p => Math.floor(p));
}