Samuel Enocsson
e29bc8ee80
After the binary search converges, also simulate predicted rating at required±1 average. Display the three rows in the modal so the user can see how sharp the requirement is — e.g. whether averaging 1 point lower costs them 1 point of predicted rating or 5.
82 lines
3.0 KiB
JavaScript
82 lines
3.0 KiB
JavaScript
const { calculatePredictedRating, getNextPDGAUpdateDate } = require('./rating-calculator');
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const logger = require('../logger');
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function calculateRequiredAverage(roundRatings, targetRating, numRounds) {
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if (!Array.isArray(roundRatings) || roundRatings.length === 0) {
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const err = new Error('No round history');
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err.code = 'NO_ROUNDS';
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throw err;
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}
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const currentPredicted = calculatePredictedRating(roundRatings).rating;
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const nextUpdate = getNextPDGAUpdateDate();
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const syntheticDate = new Date(nextUpdate.getTime() - 24 * 60 * 60 * 1000);
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const simulate = (R) => {
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const synthetic = [];
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for (let i = 0; i < numRounds; i++) {
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synthetic.push({ rating: R, date: syntheticDate, competition: 'TARGET_SIM' });
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}
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return calculatePredictedRating([...roundRatings, ...synthetic]).rating;
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};
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let lo = 400;
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let hi = 1200;
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let iterations = 0;
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const maxIterations = 30;
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let exactMatchAvg = null;
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while (iterations < maxIterations && (hi - lo) >= 0.5) {
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const mid = (lo + hi) / 2;
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const predicted = simulate(mid);
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if (predicted === targetRating) {
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exactMatchAvg = mid;
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// Narrow toward smaller R that still hits target — but break to bound iterations.
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hi = mid;
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} else if (predicted < targetRating) {
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lo = mid;
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} else {
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hi = mid;
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}
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iterations++;
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}
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const candidate = exactMatchAvg !== null ? exactMatchAvg : (lo + hi) / 2;
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const requiredAverage = Math.round(candidate * 10) / 10;
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const simulatedPredicted = simulate(requiredAverage);
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let warning = null;
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if (requiredAverage >= 1199.5) {
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warning = 'Target may be unreachable with this number of rounds within the simulated range [400, 1200].';
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} else if (requiredAverage <= 400.5) {
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warning = 'Required average is at the lower bound — target may already be exceeded or rounds would drag rating down.';
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} else if (requiredAverage > 1050) {
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warning = 'Required average is extremely high (>1050) — practically very difficult.';
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} else if (requiredAverage < 600) {
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warning = 'Required average is very low (<600) — check that your target is reasonable.';
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} else if (iterations >= maxIterations && Math.abs(simulatedPredicted - targetRating) > 1) {
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warning = 'Could not converge precisely; result is approximate.';
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}
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const lowerAvg = Math.max(400, Math.round((requiredAverage - 1) * 10) / 10);
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const upperAvg = Math.min(1200, Math.round((requiredAverage + 1) * 10) / 10);
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const sensitivity = {
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lower: { average: lowerAvg, predicted: simulate(lowerAvg) },
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target: { average: requiredAverage, predicted: simulatedPredicted },
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upper: { average: upperAvg, predicted: simulate(upperAvg) }
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};
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logger.debug(`Target rating calc: target=${targetRating} rounds=${numRounds} → avg=${requiredAverage} (iterations=${iterations}, simulated=${simulatedPredicted})`);
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return {
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requiredAverage,
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currentPredicted,
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simulatedPredicted,
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iterations,
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warning,
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sensitivity
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};
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}
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module.exports = { calculateRequiredAverage };
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