GraphNG: sort ascending if the values appear reversed (#30405)

packages/grafana-ui/src/components/GraphNG/GraphNG.tsx

@@ -29,7 +29,7 @@ import { isNumber } from 'lodash';
 const defaultFormatter = (v: any) => (v == null ? '-' : v.toFixed(1));
 
 export interface XYFieldMatchers {
-  x: FieldMatcher;
+  x: FieldMatcher; // first match
   y: FieldMatcher;
 }
 export interface GraphNGProps extends Omit<PlotProps, 'data' | 'config'> {

packages/grafana-ui/src/components/GraphNG/utils.test.ts

 import { ArrayVector, DataFrame, FieldType, toDataFrame } from '@grafana/data';
 import { AlignedFrameWithGapTest } from '../uPlot/types';
-import { alignDataFrames } from './utils';
+import { alignDataFrames, isLikelyAscendingVector } from './utils';
 
 describe('alignDataFrames', () => {
   describe('aligned frame', () => {
@@ -215,4 +215,31 @@ describe('alignDataFrames', () => {
       });
     });
   });
+
+  describe('check ascending data', () => {
+    it('simple ascending', () => {
+      const v = new ArrayVector([1, 2, 3, 4, 5]);
+      expect(isLikelyAscendingVector(v)).toBeTruthy();
+    });
+    it('simple ascending with null', () => {
+      const v = new ArrayVector([null, 2, 3, 4, null]);
+      expect(isLikelyAscendingVector(v)).toBeTruthy();
+    });
+    it('single value', () => {
+      const v = new ArrayVector([null, null, null, 4, null]);
+      expect(isLikelyAscendingVector(v)).toBeTruthy();
+      expect(isLikelyAscendingVector(new ArrayVector([4]))).toBeTruthy();
+      expect(isLikelyAscendingVector(new ArrayVector([]))).toBeTruthy();
+    });
+
+    it('middle values', () => {
+      const v = new ArrayVector([null, null, 5, 4, null]);
+      expect(isLikelyAscendingVector(v)).toBeFalsy();
+    });
+
+    it('decending', () => {
+      expect(isLikelyAscendingVector(new ArrayVector([7, 6, null]))).toBeFalsy();
+      expect(isLikelyAscendingVector(new ArrayVector([7, 8, 6]))).toBeFalsy();
+    });
+  });
 });

packages/grafana-ui/src/components/GraphNG/utils.ts

@@ -9,6 +9,8 @@ import {
   FieldType,
   FieldState,
   DataFrameFieldIndex,
+  sortDataFrame,
+  Vector,
 } from '@grafana/data';
 import { AlignedFrameWithGapTest } from '../uPlot/types';
 import uPlot, { AlignedData, JoinNullMode } from 'uplot';
@@ -16,24 +18,23 @@ import { XYFieldMatchers } from './GraphNG';
 
 // the results ofter passing though data
 export interface XYDimensionFields {
-  x: Field[];
-  y: Field[];
+  x: Field; // independent axis (cause)
+  y: Field[]; // dependent axis (effect)
 }
 
 export function mapDimesions(match: XYFieldMatchers, frame: DataFrame, frames?: DataFrame[]): XYDimensionFields {
-  const out: XYDimensionFields = {
-    x: [],
-    y: [],
-  };
+  let x: Field | undefined;
+  const y: Field[] = [];
+
   for (const field of frame.fields) {
-    if (match.x(field, frame, frames ?? [])) {
-      out.x.push(field);
+    if (!x && match.x(field, frame, frames ?? [])) {
+      x = field;
     }
     if (match.y(field, frame, frames ?? [])) {
-      out.y.push(field);
+      y.push(field);
     }
   }
-  return out;
+  return { x: x as Field, y };
 }
 
 /**
@@ -58,26 +59,29 @@ export function alignDataFrames(frames: DataFrame[], fields?: XYFieldMatchers):
   }
 
   for (let frameIndex = 0; frameIndex < frames.length; frameIndex++) {
-    const frame = frames[frameIndex];
-    const dims = mapDimesions(fields, frame, frames);
+    let frame = frames[frameIndex];
+    let dims = mapDimesions(fields, frame, frames);
 
-    if (!(dims.x.length && dims.y.length)) {
+    if (!(dims.x && dims.y.length)) {
       continue; // no numeric and no time fields
     }
 
-    if (dims.x.length > 1) {
-      throw new Error('Only a single x field is supported');
+    // Quick check that x is ascending order
+    if (!isLikelyAscendingVector(dims.x.values)) {
+      const xIndex = frame.fields.indexOf(dims.x);
+      frame = sortDataFrame(frame, xIndex);
+      dims = mapDimesions(fields, frame, frames);
     }
 
     let nullModesFrame: JoinNullMode[] = [0];
 
     // Add the first X axis
     if (!sourceFields.length) {
-      sourceFields.push(dims.x[0]);
+      sourceFields.push(dims.x);
     }
 
     const alignedData: AlignedData = [
-      dims.x[0].values.toArray(), // The x axis (time)
+      dims.x.values.toArray(), // The x axis (time)
     ];
 
     for (let fieldIndex = 0; fieldIndex < frame.fields.length; fieldIndex++) {
@@ -150,3 +154,34 @@ export function alignDataFrames(frames: DataFrame[], fields?: XYFieldMatchers):
     },
   };
 }
+
+// Quick test if the first and last points look to be ascending
+export function isLikelyAscendingVector(data: Vector): boolean {
+  let first: any = undefined;
+
+  for (let idx = 0; idx < data.length; idx++) {
+    const v = data.get(idx);
+    if (v != null) {
+      if (first != null) {
+        if (first > v) {
+          return false; // descending
+        }
+        break;
+      }
+      first = v;
+    }
+  }
+
+  let idx = data.length - 1;
+  while (idx >= 0) {
+    const v = data.get(idx--);
+    if (v != null) {
+      if (first > v) {
+        return false;
+      }
+      return true;
+    }
+  }
+
+  return true; // only one non-null point
+}