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https://github.com/prometheus/prometheus.git
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Update histogram math (#13680)
ui: Fix many edge cases of rendering a histogram --------- Signed-off-by: Manik Rana <manikrana54@gmail.com>
This commit is contained in:
Manik Rana
GitHub
parent
c94c5b64c3
commit
c9bc1c2be0
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@ -2,22 +2,104 @@ import React, { FC } from 'react';
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import { UncontrolledTooltip } from 'reactstrap';
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import { Histogram } from '../../types/types';
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import { bucketRangeString } from './DataTable';
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import {
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calculateDefaultExpBucketWidth,
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findMinPositive,
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findMaxNegative,
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findZeroAxisLeft,
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showZeroAxis,
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findZeroBucket,
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ScaleType,
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} from './HistogramHelpers';
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type ScaleType = 'linear' | 'exponential';
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interface HistogramChartProps {
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histogram: Histogram;
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index: number;
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scale: ScaleType;
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}
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const HistogramChart: FC<{ histogram: Histogram; index: number; scale: ScaleType }> = ({ index, histogram, scale }) => {
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const HistogramChart: FC<HistogramChartProps> = ({ index, histogram, scale }) => {
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const { buckets } = histogram;
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const rangeMax = buckets ? parseFloat(buckets[buckets.length - 1][2]) : 0;
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const countMax = buckets ? buckets.map((b) => parseFloat(b[3])).reduce((a, b) => Math.max(a, b)) : 0;
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if (!buckets || buckets.length === 0) {
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return <div>No data</div>;
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}
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const formatter = Intl.NumberFormat('en', { notation: 'compact' });
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const positiveBuckets = buckets?.filter((b) => parseFloat(b[1]) >= 0); // we only want to show buckets with range >= 0
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const xLabelTicks = scale === 'linear' ? [0.25, 0.5, 0.75, 1] : [1];
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// For linear scales, the count of a histogram bucket is represented by its area rather than its height. This means it considers
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// both the count and the range (width) of the bucket. For this, we can set the height of the bucket proportional
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// to its frequency density (fd). The fd is the count of the bucket divided by the width of the bucket.
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const fds = [];
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for (const bucket of buckets) {
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const left = parseFloat(bucket[1]);
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const right = parseFloat(bucket[2]);
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const count = parseFloat(bucket[3]);
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const width = right - left;
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// This happens when a user want observations of precisely zero to be included in the zero bucket
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if (width === 0) {
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fds.push(0);
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continue;
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}
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fds.push(count / width);
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}
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const fdMax = Math.max(...fds);
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const first = buckets[0];
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const last = buckets[buckets.length - 1];
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const rangeMax = parseFloat(last[2]);
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const rangeMin = parseFloat(first[1]);
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const countMax = Math.max(...buckets.map((b) => parseFloat(b[3])));
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const defaultExpBucketWidth = calculateDefaultExpBucketWidth(last, buckets);
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const maxPositive = rangeMax > 0 ? rangeMax : 0;
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const minPositive = findMinPositive(buckets);
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const maxNegative = findMaxNegative(buckets);
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const minNegative = parseFloat(first[1]) < 0 ? parseFloat(first[1]) : 0;
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// Calculate the borders of positive and negative buckets in the exponential scale from left to right
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const startNegative = minNegative !== 0 ? -Math.log(Math.abs(minNegative)) : 0;
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const endNegative = maxNegative !== 0 ? -Math.log(Math.abs(maxNegative)) : 0;
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const startPositive = minPositive !== 0 ? Math.log(minPositive) : 0;
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const endPositive = maxPositive !== 0 ? Math.log(maxPositive) : 0;
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console.log(
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'startNegative',
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startNegative,
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'endNegative',
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endNegative,
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'startPositive',
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startPositive,
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'endPositive',
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endPositive
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);
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// Calculate the width of negative, positive, and all exponential bucket ranges on the x-axis
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const xWidthNegative = endNegative - startNegative;
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const xWidthPositive = endPositive - startPositive;
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const xWidthTotal = xWidthNegative + defaultExpBucketWidth + xWidthPositive;
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console.log('xWidthNegative', xWidthNegative, 'xWidthPositive', xWidthPositive, 'xWidthTotal', xWidthTotal);
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const zeroBucketIdx = findZeroBucket(buckets);
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const zeroAxisLeft = findZeroAxisLeft(
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scale,
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rangeMin,
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rangeMax,
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minPositive,
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maxNegative,
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zeroBucketIdx,
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xWidthNegative,
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xWidthTotal,
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defaultExpBucketWidth
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);
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const zeroAxis = showZeroAxis(zeroAxisLeft);
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return (
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<div className="histogram-y-wrapper">
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<div className="histogram-y-labels">
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{[1, 0.75, 0.5, 0.25].map((i) => (
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<div key={i} className="histogram-y-label">
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{formatter.format(countMax * i)}
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{scale === 'linear' ? '' : formatter.format(countMax * i)}
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</div>
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))}
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<div key={0} className="histogram-y-label" style={{ height: 0 }}>
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@ -31,62 +113,228 @@ const HistogramChart: FC<{ histogram: Histogram; index: number; scale: ScaleType
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<div className="histogram-y-grid" style={{ bottom: i * 100 + '%' }}></div>
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<div className="histogram-y-tick" style={{ bottom: i * 100 + '%' }}></div>
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<div className="histogram-x-grid" style={{ left: i * 100 + '%' }}></div>
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<div className="histogram-x-tick" style={{ left: i * 100 + '%' }}></div>
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</React.Fragment>
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))}
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{positiveBuckets?.map((b, bIdx) => {
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const bucketIdx = `bucket-${index}-${bIdx}-${Math.ceil(parseFloat(b[3]) * 100)}`;
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const bucketLeft =
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scale === 'linear' ? (parseFloat(b[1]) / rangeMax) * 100 + '%' : (bIdx / positiveBuckets.length) * 100 + '%';
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const bucketWidth =
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scale === 'linear'
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? ((parseFloat(b[2]) - parseFloat(b[1])) / rangeMax) * 100 + '%'
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: 100 / positiveBuckets.length + '%';
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return (
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<React.Fragment key={bIdx}>
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<div
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id={bucketIdx}
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className="histogram-bucket-slot"
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style={{
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left: bucketLeft,
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width: bucketWidth,
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}}
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>
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<div
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id={bucketIdx}
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className="histogram-bucket"
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style={{
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height: (parseFloat(b[3]) / countMax) * 100 + '%',
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}}
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></div>
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<UncontrolledTooltip
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style={{ maxWidth: 'unset', padding: 10, textAlign: 'left' }}
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placement="bottom"
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target={bucketIdx}
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>
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<strong>range:</strong> {bucketRangeString(b)}
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<br />
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<strong>count:</strong> {b[3]}
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</UncontrolledTooltip>
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</div>
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</React.Fragment>
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);
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})}
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<div className="histogram-x-tick" style={{ left: '0%' }}></div>
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<div className="histogram-x-tick" style={{ left: zeroAxisLeft }}></div>
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<div className="histogram-x-grid" style={{ left: zeroAxisLeft }}></div>
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<div className="histogram-x-tick" style={{ left: '100%' }}></div>
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<RenderHistogramBars
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buckets={buckets}
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scale={scale}
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rangeMin={rangeMin}
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rangeMax={rangeMax}
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index={index}
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fds={fds}
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fdMax={fdMax}
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countMax={countMax}
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defaultExpBucketWidth={defaultExpBucketWidth}
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minPositive={minPositive}
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maxNegative={maxNegative}
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startPositive={startPositive}
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startNegative={startNegative}
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xWidthPositive={xWidthPositive}
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xWidthNegative={xWidthNegative}
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xWidthTotal={xWidthTotal}
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/>
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<div className="histogram-axes"></div>
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</div>
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<div className="histogram-x-labels">
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<div key={0} className="histogram-x-label" style={{ width: 0 }}>
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0
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<div className="histogram-x-label">
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<React.Fragment>
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<div style={{ position: 'absolute', left: 0 }}>{formatter.format(rangeMin)}</div>
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{rangeMin < 0 && zeroAxis && <div style={{ position: 'absolute', left: zeroAxisLeft }}>0</div>}
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<div style={{ position: 'absolute', right: 0 }}>{formatter.format(rangeMax)}</div>
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</React.Fragment>
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</div>
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{xLabelTicks.map((i) => (
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<div key={i} className="histogram-x-label">
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<div style={{ position: 'absolute', right: i === 1 ? 0 : -18 }}>{formatter.format(rangeMax * i)}</div>
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</div>
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))}
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</div>
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</div>
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</div>
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);
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};
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interface RenderHistogramProps {
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buckets: [number, string, string, string][];
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scale: ScaleType;
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rangeMin: number;
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rangeMax: number;
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index: number;
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fds: number[];
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fdMax: number;
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countMax: number;
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defaultExpBucketWidth: number;
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minPositive: number;
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maxNegative: number;
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startPositive: number;
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startNegative: number;
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xWidthNegative: number;
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xWidthPositive: number;
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xWidthTotal: number;
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}
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const RenderHistogramBars: FC<RenderHistogramProps> = ({
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buckets,
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scale,
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rangeMin,
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rangeMax,
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index,
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fds,
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fdMax,
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countMax,
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defaultExpBucketWidth,
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minPositive,
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maxNegative,
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startPositive,
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startNegative,
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xWidthNegative,
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xWidthPositive,
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xWidthTotal,
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}) => {
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return (
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<React.Fragment>
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{buckets.map((b, bIdx) => {
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const left = parseFloat(b[1]);
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const right = parseFloat(b[2]);
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const count = parseFloat(b[3]);
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const bucketIdx = `bucket-${index}-${bIdx}-${Math.ceil(parseFloat(b[3]) * 100)}`;
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const logWidth = Math.abs(Math.log(Math.abs(right)) - Math.log(Math.abs(left)));
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const expBucketWidth = logWidth === 0 ? defaultExpBucketWidth : logWidth;
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let bucketWidth = '';
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let bucketLeft = '';
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let bucketHeight = '';
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switch (scale) {
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case 'linear':
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bucketWidth = ((right - left) / (rangeMax - rangeMin)) * 100 + '%';
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bucketLeft = ((left - rangeMin) / (rangeMax - rangeMin)) * 100 + '%';
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if (left === 0 && right === 0) {
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bucketLeft = '0%'; // do not render zero-width zero bucket
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bucketWidth = '0%';
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}
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bucketHeight = (fds[bIdx] / fdMax) * 100 + '%';
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break;
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case 'exponential':
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let adjust = 0; // if buckets are all positive/negative, we need to remove the width of the zero bucket
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if (minPositive === 0 || maxNegative === 0) {
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adjust = defaultExpBucketWidth;
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}
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bucketWidth = (expBucketWidth / (xWidthTotal - adjust)) * 100 + '%';
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if (left < 0) {
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// negative buckets boundary
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bucketLeft = (-(Math.log(Math.abs(left)) + startNegative) / (xWidthTotal - adjust)) * 100 + '%';
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} else {
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// positive buckets boundary
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bucketLeft =
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((Math.log(left) - startPositive + defaultExpBucketWidth + xWidthNegative - adjust) /
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(xWidthTotal - adjust)) *
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100 +
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'%';
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}
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if (left < 0 && right > 0) {
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// if the bucket crosses the zero axis
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bucketLeft = (xWidthNegative / xWidthTotal) * 100 + '%';
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}
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if (left === 0 && right === 0) {
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// do not render zero width zero bucket
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bucketLeft = '0%';
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bucketWidth = '0%';
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}
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bucketHeight = (count / countMax) * 100 + '%';
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break;
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default:
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throw new Error('Invalid scale');
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}
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console.log(
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'[',
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left,
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',',
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right,
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']',
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'\n',
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'fds[bIdx]',
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fds[bIdx],
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'\n',
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'fdMax',
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fdMax,
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'\n',
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'bucketIdx',
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bucketIdx,
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'\n',
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'bucketLeft',
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bucketLeft,
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'\n',
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'bucketWidth',
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bucketWidth,
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'\n',
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'bucketHeight',
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bucketHeight,
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'\n',
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'defaultExpBucketWidth',
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defaultExpBucketWidth,
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'\n',
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'expBucketWidth',
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expBucketWidth,
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'\n',
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'startNegative',
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startNegative,
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'\n',
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'startPositive',
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startPositive,
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'\n',
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'minPositive',
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minPositive,
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'\n',
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'maxNegative',
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maxNegative,
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'xWidthNegative',
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xWidthNegative,
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'\n',
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'xWidthTotal',
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xWidthTotal,
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'\n',
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'xWidthPositive',
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xWidthPositive,
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'\n'
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);
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return (
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<React.Fragment key={bIdx}>
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<div
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id={bucketIdx}
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className="histogram-bucket-slot"
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style={{
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left: bucketLeft,
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width: bucketWidth,
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}}
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>
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<div
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id={bucketIdx}
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className="histogram-bucket"
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style={{
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height: bucketHeight,
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}}
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></div>
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<UncontrolledTooltip
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style={{ maxWidth: 'unset', padding: 10, textAlign: 'left' }}
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placement="bottom"
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target={bucketIdx}
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>
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<strong>range:</strong> {bucketRangeString(b)}
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<br />
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<strong>count:</strong> {count}
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</UncontrolledTooltip>
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</div>
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</React.Fragment>
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);
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})}
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</React.Fragment>
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);
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};
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export default HistogramChart;
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126
web/ui/react-app/src/pages/graph/HistogramHelpers.ts
Normal file
126
web/ui/react-app/src/pages/graph/HistogramHelpers.ts
Normal file
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@ -0,0 +1,126 @@
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export type ScaleType = 'linear' | 'exponential';
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// Calculates a default width of exponential histogram bucket ranges. If the last bucket is [0, 0],
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// the width is calculated using the second to last bucket. returns error if the last bucket is [-0, 0],
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export function calculateDefaultExpBucketWidth(
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last: [number, string, string, string],
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buckets: [number, string, string, string][]
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): number {
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if (parseFloat(last[2]) === 0 || parseFloat(last[1]) === 0) {
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if (buckets.length > 1) {
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return Math.abs(
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Math.log(Math.abs(parseFloat(buckets[buckets.length - 2][2]))) -
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Math.log(Math.abs(parseFloat(buckets[buckets.length - 2][1])))
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);
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} else {
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throw new Error('Only one bucket in histogram ([-0, 0]). Cannot calculate defaultExpBucketWidth.');
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}
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} else {
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return Math.abs(Math.log(Math.abs(parseFloat(last[2]))) - Math.log(Math.abs(parseFloat(last[1]))));
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}
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}
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// Finds the lowest positive value from the bucket ranges
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// Returns 0 if no positive values are found or if there are no buckets.
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export function findMinPositive(buckets: [number, string, string, string][]) {
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if (!buckets || buckets.length === 0) {
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return 0; // no buckets
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}
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for (let i = 0; i < buckets.length; i++) {
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const right = parseFloat(buckets[i][2]);
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const left = parseFloat(buckets[i][1]);
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if (left > 0) {
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return left;
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}
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if (left < 0 && right > 0) {
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return right;
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}
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if (i === buckets.length - 1) {
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if (right > 0) {
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return right;
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}
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}
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}
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return 0; // all buckets are negative
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}
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// Finds the lowest negative value from the bucket ranges
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// Returns 0 if no negative values are found or if there are no buckets.
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export function findMaxNegative(buckets: [number, string, string, string][]) {
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if (!buckets || buckets.length === 0) {
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return 0; // no buckets
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}
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for (let i = 0; i < buckets.length; i++) {
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const right = parseFloat(buckets[i][2]);
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const left = parseFloat(buckets[i][1]);
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const prevRight = i > 0 ? parseFloat(buckets[i - 1][2]) : 0;
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if (right >= 0) {
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if (i === 0) {
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if (left < 0) {
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return left; // return the first negative bucket
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}
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return 0; // all buckets are positive
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}
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return prevRight; // return the last negative bucket
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}
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}
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console.log('findmaxneg returning: ', buckets[buckets.length - 1][2]);
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return parseFloat(buckets[buckets.length - 1][2]); // all buckets are negative
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}
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// Calculates the left position of the zero axis as a percentage string.
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export function findZeroAxisLeft(
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scale: ScaleType,
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rangeMin: number,
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rangeMax: number,
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minPositive: number,
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maxNegative: number,
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zeroBucketIdx: number,
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widthNegative: number,
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widthTotal: number,
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expBucketWidth: number
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): string {
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if (scale === 'linear') {
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return ((0 - rangeMin) / (rangeMax - rangeMin)) * 100 + '%';
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} else {
|
||||
if (maxNegative === 0) {
|
||||
return '0%';
|
||||
}
|
||||
if (minPositive === 0) {
|
||||
return '100%';
|
||||
}
|
||||
if (zeroBucketIdx === -1) {
|
||||
// if there is no zero bucket, we must zero axis between buckets around zero
|
||||
return (widthNegative / widthTotal) * 100 + '%';
|
||||
}
|
||||
if ((widthNegative + 0.5 * expBucketWidth) / widthTotal > 0) {
|
||||
return ((widthNegative + 0.5 * expBucketWidth) / widthTotal) * 100 + '%';
|
||||
} else {
|
||||
return '0%';
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Determines if the zero axis should be shown such that the zero label does not overlap with the range labels.
|
||||
// The zero axis is shown if it is between 5% and 95% of the graph.
|
||||
export function showZeroAxis(zeroAxisLeft: string) {
|
||||
const axisNumber = parseFloat(zeroAxisLeft.slice(0, -1));
|
||||
if (5 < axisNumber && axisNumber < 95) {
|
||||
return true;
|
||||
}
|
||||
return false;
|
||||
}
|
||||
|
||||
// Finds the index of the bucket whose range includes zero
|
||||
export function findZeroBucket(buckets: [number, string, string, string][]): number {
|
||||
for (let i = 0; i < buckets.length; i++) {
|
||||
const left = parseFloat(buckets[i][1]);
|
||||
const right = parseFloat(buckets[i][2]);
|
||||
if (left <= 0 && right >= 0) {
|
||||
return i;
|
||||
}
|
||||
}
|
||||
return -1;
|
||||
}
|
||||
Loading…
Reference in a new issue