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Merge pull request #4531 from rizka10/master 

Improve summing of poll percentages to 100
This commit is contained in:
Régis Hanol 2016-11-03 10:42:59 +01:00 committed by GitHub
parent b825a6bc7f 22cfbafb60
commit 71fa9541fa
1 changed files with 20 additions and 8 deletions
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26
plugins/poll/assets/javascripts/lib/even-round.js.es6
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@ -1,17 +1,29 @@
// stolen from http://stackoverflow.com/a/13484088/11983 // works as described on http://stackoverflow.com/a/13483710
function sumsUpTo100(percentages) { function sumsUpTo100(percentages) {
return percentages.map(p => Math.floor(p)).reduce((a, b) => a + b) === 100; return percentages.map(p => Math.floor(p)).reduce((a, b) => a + b) === 100;
} }
export default (percentages) => { export default (percentages) => {
const sumOfDecimals = Math.ceil(percentages.map(a => a % 1).reduce((a, b) => a + b)); var decimals = percentages.map(a => a % 1);
// compensate error by adding 1 to the first n "non-zero" items const sumOfDecimals = Math.ceil(decimals.reduce((a, b) => a + b));
for (let i = 0, max = percentages.length; i < sumOfDecimals && i < max; i++) { // compensate error by adding 1 to n items with the greatest decimal part
if (percentages[i] > 0) { for (let i = 0, max = decimals.length; i < sumOfDecimals && i < max; i++) {
percentages[i] = ++percentages[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 // quit early when there is a rounding issue
if (sumsUpTo100(percentages)) break; if (sumsUpTo100(percentages)) break;
} }
}
return percentages.map(p => Math.floor(p)); return percentages.map(p => Math.floor(p));
}; };