Histogram: Replace null values (#83195)

packages/grafana-data/src/transformations/transformers/histogram.test.ts

@@ -22,6 +22,14 @@ describe('histogram frames frames', () => {
       fields: [{ name: 'C', type: FieldType.number, values: [5, 6, 7, 8, 9] }],
     });
 
+    const series3 = toDataFrame({
+      fields: [{ name: 'D', type: FieldType.number, values: [1, 2, 3, null, null] }],
+    });
+
+    const series4 = toDataFrame({
+      fields: [{ name: 'E', type: FieldType.number, values: [4, 5, null, 6, null], config: { noValue: '0' } }],
+    });
+
     const out = histogramFieldsToFrame(buildHistogram([series1, series2])!);
     expect(
       out.fields.map((f) => ({
@@ -188,5 +196,87 @@ describe('histogram frames frames', () => {
         },
       ]
     `);
+
+    // NULLs filtering test
+    const out3 = histogramFieldsToFrame(buildHistogram([series3])!);
+    expect(
+      out3.fields.map((f) => ({
+        name: f.name,
+        values: f.values,
+      }))
+    ).toMatchInlineSnapshot(`
+      [
+        {
+          "name": "xMin",
+          "values": [
+            1,
+            2,
+            3,
+          ],
+        },
+        {
+          "name": "xMax",
+          "values": [
+            2,
+            3,
+            4,
+          ],
+        },
+        {
+          "name": "D",
+          "values": [
+            1,
+            1,
+            1,
+          ],
+        },
+      ]
+    `);
+
+    // noValue nulls test
+    const out4 = histogramFieldsToFrame(buildHistogram([series4])!);
+    expect(
+      out4.fields.map((f) => ({
+        name: f.name,
+        values: f.values,
+        config: f.config,
+      }))
+    ).toMatchInlineSnapshot(`
+      [
+        {
+          "config": {},
+          "name": "xMin",
+          "values": [
+            0,
+            4,
+            5,
+            6,
+          ],
+        },
+        {
+          "config": {},
+          "name": "xMax",
+          "values": [
+            1,
+            5,
+            6,
+            7,
+          ],
+        },
+        {
+          "config": {
+            "noValue": "0",
+            "unit": undefined,
+          },
+          "name": "E",
+          "values": [
+            2,
+            1,
+            1,
+            1,
+          ],
+        },
+      ]
+    `);
   });
 });

packages/grafana-data/src/transformations/transformers/histogram.ts

@@ -8,6 +8,7 @@ import { roundDecimals } from '../../utils';
 
 import { DataTransformerID } from './ids';
 import { AlignedData, join } from './joinDataFrames';
+import { nullToValueField } from './nulls/nullToValue';
 import { transformationsVariableSupport } from './utils';
 
 /**
@@ -334,6 +335,26 @@ export function buildHistogram(frames: DataFrame[], options?: HistogramTransform
   let bucketCount = options?.bucketCount ?? DEFAULT_BUCKET_COUNT;
   let bucketOffset = options?.bucketOffset ?? 0;
 
+  // replace or filter nulls from numeric fields
+  frames = frames.map((frame) => {
+    return {
+      ...frame,
+      fields: frame.fields.map((field) => {
+        if (field.type === FieldType.number) {
+          const noValue = Number(field.config.noValue);
+
+          if (!Number.isNaN(noValue)) {
+            field = nullToValueField(field, noValue);
+          } else {
+            field = { ...field, values: field.values.filter((v) => v != null) };
+          }
+        }
+
+        return field;
+      }),
+    };
+  });
+
   // if bucket size is auto, try to calc from all numeric fields
   if (!bucketSize || bucketSize < 0) {
     let allValues: number[] = [];
@@ -347,8 +368,6 @@ export function buildHistogram(frames: DataFrame[], options?: HistogramTransform
       }
     }
 
-    allValues = allValues.filter((v) => v != null);
-
     allValues.sort((a, b) => a - b);
 
     let smallestDelta = Infinity;

packages/grafana-data/src/transformations/transformers/nulls/nullToValue.ts

@@ -1,27 +1,31 @@
-import { DataFrame } from '../../../types';
+import { DataFrame, Field } from '../../../types';
 
 export function nullToValue(frame: DataFrame) {
   return {
     ...frame,
     fields: frame.fields.map((field) => {
-      const noValue = +field.config?.noValue!;
+      const noValue = Number(field.config.noValue);
 
       if (!Number.isNaN(noValue)) {
-        const transformedVals = field.values.slice();
-
-        for (let i = 0; i < transformedVals.length; i++) {
-          if (transformedVals[i] === null) {
-            transformedVals[i] = noValue;
-          }
-        }
-
-        return {
-          ...field,
-          values: transformedVals,
-        };
+        return nullToValueField(field, noValue);
       } else {
         return field;
       }
     }),
   };
 }
+
+export function nullToValueField(field: Field, noValue: number) {
+  const transformedVals = field.values.slice();
+
+  for (let i = 0; i < transformedVals.length; i++) {
+    if (transformedVals[i] === null) {
+      transformedVals[i] = noValue;
+    }
+  }
+
+  return {
+    ...field,
+    values: transformedVals,
+  };
+}