FIX: use an algorithm that doesn't re-order percentages when rounding them up to 100% in single choice polls
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@ -5,17 +5,16 @@ export default Em.Component.extend({
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tagName: "ul",
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classNames: ["results"],
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@computed("poll.voters", "poll.options.[]", "poll.type")
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options() {
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@computed("poll.voters", "poll.type", "poll.options.[]")
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options(voters, type) {
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const options = this.get("poll.options");
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const voters = this.get("poll.voters");
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let percentages = voters === 0 ?
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Array(options.length).fill(0) :
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_.map(options, o => 100 * o.get("votes") / voters);
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// properly round percentages
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if (this.get("poll.type") === "multiple") {
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if (type === "multiple") {
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// when the poll is multiple choices, just "round down"
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percentages = percentages.map(p => Math.floor(p));
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} else {
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@ -34,7 +33,7 @@ export default Em.Component.extend({
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});
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});
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return this.get("poll.options");
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return options;
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}
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});
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@ -1,8 +1,9 @@
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// stolen from http://stackoverflow.com/a/13485888/11983
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// stolen from http://stackoverflow.com/a/13484088/11983
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export default (percentages) => {
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const off = 100 - _.reduce(percentages, (acc, x) => acc + Math.round(x), 0);
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return _.chain(percentages)
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.sortBy(x => Math.round(x) - x)
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.map((x, i) => Math.round(x) + (off > i) - (i >= (percentages.length + off)))
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.value();
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const sumOfDecimals = Math.ceil(percentages.map(a => a % 1).reduce((a, b) => a + b));
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// compensate error by adding 1 to the first n items
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for (let i = 0; i < sumOfDecimals; i++) {
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percentages[i] = ++percentages[i];
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}
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return percentages.map(a => Math.floor(a));
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};
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