Change algorithm for auto interval

elastic · Sep 1, 2020 · 4b2ae64 · 4b2ae64
1 parent 0b3259d
commit 4b2ae64
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Showing 2 changed files with 30 additions and 54 deletions.
diff --git a/src/plugins/data/common/search/aggs/buckets/lib/histogram_calculate_interval.test.ts b/src/plugins/data/common/search/aggs/buckets/lib/histogram_calculate_interval.test.ts
@@ -22,11 +22,6 @@ import {
   CalculateHistogramIntervalParams,
 } from './histogram_calculate_interval';
 
-const getLargestPossibleInterval = (params: CalculateHistogramIntervalParams) => {
-  const diff = params.values!.max - params.values!.min;
-  return diff / params.maxBucketsUiSettings;
-};
-
 describe('calculateHistogramInterval', () => {
   describe('auto calculating mode', () => {
     let params: CalculateHistogramIntervalParams;
@@ -86,17 +81,15 @@ describe('calculateHistogramInterval', () => {
 
     describe('maxBucketsUserInput is not defined', () => {
       test('should not set interval which more than largest possible', () => {
-        const p = {
-          ...params,
-          values: {
-            min: 0,
-            max: 100,
-          },
-        };
-        const expectedInterval = getLargestPossibleInterval(p);
-
-        expect(expectedInterval).toBe(1);
-        expect(calculateHistogramInterval(p)).toBe(expectedInterval);
+        expect(
+          calculateHistogramInterval({
+            ...params,
+            values: {
+              min: 0,
+              max: 100,
+            },
+          })
+        ).toEqual(1);
       });
 
       test('should set intervals for integer numbers (diff less than maxBucketsUiSettings)', () => {
@@ -108,11 +101,11 @@ describe('calculateHistogramInterval', () => {
               max: 10,
             },
           })
-        ).toBe(1);
+        ).toEqual(0.1);
       });
 
       test('should set intervals for integer numbers (diff more than maxBucketsUiSettings)', () => {
-        // diff === 44445; interval === 2000; buckets === 22
+        // diff === 44445; interval === 500; buckets === 89
         expect(
           calculateHistogramInterval({
             ...params,
@@ -121,11 +114,12 @@ describe('calculateHistogramInterval', () => {
               max: 90123,
             },
           })
-        ).toBe(2000);
+        ).toEqual(500);
       });
 
-      test('should set intervals for float numbers (small numbers)', () => {
-        // diff === 1.655; interval === 0.03; buckets === 55
+      test('should set intervals the same for the same interval', () => {
+        // both diffs are the same
+        // diff === 1.655; interval === 0.02; buckets === 82
         expect(
           calculateHistogramInterval({
             ...params,
@@ -134,11 +128,7 @@ describe('calculateHistogramInterval', () => {
               max: 2.9,
             },
           })
-        ).toBe(0.03);
-      });
-
-      test('should set intervals for float numbers (small numbers #2)', () => {
-        // diff === 1.655; interval === 0.02; buckets === 82
+        ).toEqual(0.02);
         expect(
           calculateHistogramInterval({
             ...params,
@@ -147,7 +137,7 @@ describe('calculateHistogramInterval', () => {
               max: 2.3,
             },
           })
-        ).toBe(0.02);
+        ).toEqual(0.02);
       });
     });
   });

diff --git a/src/plugins/data/common/search/aggs/buckets/lib/histogram_calculate_interval.ts b/src/plugins/data/common/search/aggs/buckets/lib/histogram_calculate_interval.ts
@@ -64,41 +64,27 @@ const calculateForGivenInterval = (
 
 const calculateAutoInterval = (
   diff: number,
-  values: IntervalValuesRange,
   maxBucketsUiSettings: CalculateHistogramIntervalParams['maxBucketsUiSettings'],
   maxBucketsUserInput: CalculateHistogramIntervalParams['maxBucketsUserInput']
 ) => {
-  const getMaxFractionalPart = (...numbers: number[]) => {
-    return numbers.reduce((acc, n) => {
-      const [, value] = n.toString().split('.');
-      return value && value.length > acc ? value.length : acc;
-    }, 0);
-  };
+  const maxBars = Math.min(maxBucketsUiSettings, maxBucketsUserInput ?? maxBucketsUiSettings);
+  const exactInterval = diff / maxBars;
 
-  let autoBuckets: number = 0;
+  const lowerPower = Math.pow(10, Math.floor(Math.log10(exactInterval)));
 
-  if (!maxBucketsUserInput) {
-    const fractalFactor = Math.pow(10, getMaxFractionalPart(values.min, values.max));
+  const autoBuckets = diff / lowerPower;
 
-    autoBuckets = diff * fractalFactor;
-
-    if (autoBuckets > maxBucketsUiSettings) {
-      autoBuckets =
-        (Math.log10(maxBucketsUiSettings) / Math.log10(autoBuckets)) * maxBucketsUiSettings;
-    }
-
-    // For float numbers we can try to increase interval
-    if (fractalFactor > 1 && autoBuckets < maxBucketsUiSettings / 2) {
-      autoBuckets = autoBuckets * 5;
-      if (autoBuckets > maxBucketsUiSettings) {
-        autoBuckets = autoBuckets * 2;
-      }
+  if (autoBuckets > maxBars) {
+    if (autoBuckets / 2 <= maxBars) {
+      return lowerPower * 2;
+    } else if (autoBuckets / 5 <= maxBars) {
+      return lowerPower * 5;
+    } else {
+      return lowerPower * 10;
     }
   }
 
-  const bars = Math.min(maxBucketsUiSettings, maxBucketsUserInput || autoBuckets || 1);
-
-  return roundInterval(diff / bars);
+  return lowerPower;
 };
 
 export const calculateHistogramInterval = ({
@@ -121,7 +107,7 @@ export const calculateHistogramInterval = ({
 
     if (diff) {
       calculatedInterval = isAuto
-        ? calculateAutoInterval(diff, values, maxBucketsUiSettings, maxBucketsUserInput)
+        ? calculateAutoInterval(diff, maxBucketsUiSettings, maxBucketsUserInput)
         : calculateForGivenInterval(diff, calculatedInterval, maxBucketsUiSettings);
     }
   }