83 lines
3.9 KiB
JavaScript
83 lines
3.9 KiB
JavaScript
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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const JsHistogramIterator_1 = require("./JsHistogramIterator");
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const { pow, floor, log2 } = Math;
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/**
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* Used for iterating through histogram values according to percentile levels. The iteration is
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* performed in steps that start at 0% and reduce their distance to 100% according to the
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* <i>percentileTicksPerHalfDistance</i> parameter, ultimately reaching 100% when all recorded histogram
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* values are exhausted.
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*/
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class PercentileIterator extends JsHistogramIterator_1.default {
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/**
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* @param histogram The histogram this iterator will operate on
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* @param percentileTicksPerHalfDistance The number of equal-sized iteration steps per half-distance to 100%.
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*/
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constructor(histogram, percentileTicksPerHalfDistance) {
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super();
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this.percentileTicksPerHalfDistance = 0;
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this.percentileLevelToIterateTo = 0;
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this.percentileLevelToIterateFrom = 0;
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this.reachedLastRecordedValue = false;
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this.doReset(histogram, percentileTicksPerHalfDistance);
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}
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/**
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* Reset iterator for re-use in a fresh iteration over the same histogram data set.
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*
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* @param percentileTicksPerHalfDistance The number of iteration steps per half-distance to 100%.
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*/
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reset(percentileTicksPerHalfDistance) {
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this.doReset(this.histogram, percentileTicksPerHalfDistance);
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}
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doReset(histogram, percentileTicksPerHalfDistance) {
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super.resetIterator(histogram);
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this.percentileTicksPerHalfDistance = percentileTicksPerHalfDistance;
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this.percentileLevelToIterateTo = 0;
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this.percentileLevelToIterateFrom = 0;
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this.reachedLastRecordedValue = false;
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}
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hasNext() {
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if (super.hasNext())
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return true;
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if (!this.reachedLastRecordedValue && this.arrayTotalCount > 0) {
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this.percentileLevelToIterateTo = 100;
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this.reachedLastRecordedValue = true;
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return true;
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}
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return false;
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}
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incrementIterationLevel() {
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this.percentileLevelToIterateFrom = this.percentileLevelToIterateTo;
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// The choice to maintain fixed-sized "ticks" in each half-distance to 100% [starting
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// from 0%], as opposed to a "tick" size that varies with each interval, was made to
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// make the steps easily comprehensible and readable to humans. The resulting percentile
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// steps are much easier to browse through in a percentile distribution output, for example.
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//
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// We calculate the number of equal-sized "ticks" that the 0-100 range will be divided
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// by at the current scale. The scale is detemined by the percentile level we are
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// iterating to. The following math determines the tick size for the current scale,
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// and maintain a fixed tick size for the remaining "half the distance to 100%"
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// [from either 0% or from the previous half-distance]. When that half-distance is
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// crossed, the scale changes and the tick size is effectively cut in half.
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// percentileTicksPerHalfDistance = 5
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// percentileReportingTicks = 10,
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const percentileReportingTicks = this.percentileTicksPerHalfDistance *
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pow(2, floor(log2(100 / (100 - this.percentileLevelToIterateTo))) + 1);
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this.percentileLevelToIterateTo += 100 / percentileReportingTicks;
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}
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reachedIterationLevel() {
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if (this.countAtThisValue === 0) {
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return false;
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}
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const currentPercentile = (100 * this.totalCountToCurrentIndex) / this.arrayTotalCount;
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return currentPercentile >= this.percentileLevelToIterateTo;
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}
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getPercentileIteratedTo() {
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return this.percentileLevelToIterateTo;
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}
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getPercentileIteratedFrom() {
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return this.percentileLevelToIterateFrom;
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}
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}
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exports.default = PercentileIterator;
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//# sourceMappingURL=PercentileIterator.js.map
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