Alerting: Support median in reduce expressions (#91119)

* Alerting: support median in reduce expressions

packages/grafana-data/src/transformations/fieldReducer.ts

@@ -14,6 +14,7 @@ export enum ReducerID {
   variance = 'variance',
   stdDev = 'stdDev',
   last = 'last',
+  median = 'median',
   first = 'first',
   count = 'count',
   range = 'range',
@@ -278,6 +279,14 @@ export const fieldReducers = new Registry<FieldReducerInfo>(() => [
     aliasIds: ['avg'],
     preservesUnits: true,
   },
+  {
+    id: ReducerID.median,
+    name: 'Median',
+    description: 'Median Value',
+    standard: true,
+    aliasIds: ['median'],
+    preservesUnits: true,
+  },
   {
     id: ReducerID.variance,
     name: 'Variance',

pkg/expr/mathexp/reduce.go

@@ -3,6 +3,7 @@ package mathexp
 import (
 	"fmt"
 	"math"
+	"sort"
 
 	"github.com/grafana/grafana-plugin-sdk-go/data"
 )
@@ -20,11 +21,12 @@ const (
 	ReducerMax    ReducerID = "max"
 	ReducerCount  ReducerID = "count"
 	ReducerLast   ReducerID = "last"
+	ReducerMedian ReducerID = "median"
 )
 
 // GetSupportedReduceFuncs returns collection of supported function names
 func GetSupportedReduceFuncs() []ReducerID {
-	return []ReducerID{ReducerSum, ReducerMean, ReducerMin, ReducerMax, ReducerCount, ReducerLast}
+	return []ReducerID{ReducerSum, ReducerMean, ReducerMin, ReducerMax, ReducerCount, ReducerLast, ReducerMedian}
 }
 
 func Sum(fv *Float64Field) *float64 {
@@ -98,6 +100,32 @@ func Last(fv *Float64Field) *float64 {
 	return fv.GetValue(fv.Len() - 1)
 }
 
+func Median(fv *Float64Field) *float64 {
+	values := make([]float64, 0, fv.Len())
+	for i := 0; i < fv.Len(); i++ {
+		v := fv.GetValue(i)
+		if v == nil || math.IsNaN(*v) {
+			nan := math.NaN()
+			return &nan
+		}
+		values = append(values, *v)
+	}
+
+	if len(values) == 0 {
+		nan := math.NaN()
+		return &nan
+	}
+
+	sort.Float64s(values)
+	mid := len(values) / 2
+	if len(values)%2 == 0 {
+		v := (values[mid-1] + values[mid]) / 2
+		return &v
+	} else {
+		return &values[mid]
+	}
+}
+
 func GetReduceFunc(rFunc ReducerID) (ReducerFunc, error) {
 	switch rFunc {
 	case ReducerSum:
@@ -112,6 +140,8 @@ func GetReduceFunc(rFunc ReducerID) (ReducerFunc, error) {
 		return Count, nil
 	case ReducerLast:
 		return Last, nil
+	case ReducerMedian:
+		return Median, nil
 	default:
 		return nil, fmt.Errorf("reduction %v not implemented", rFunc)
 	}

pkg/expr/mathexp/reduce_test.go

@@ -3,6 +3,7 @@ package mathexp
 import (
 	"math"
 	"math/rand"
+	"sort"
 	"testing"
 	"time"
 
@@ -90,6 +91,100 @@ func TestSeriesReduce(t *testing.T) {
 			resultsIs:   require.Equal,
 			results:     resultValuesNoErr(makeNumber("", nil, NaN)),
 		},
+		{
+			name:        "median empty series",
+			red:         "median",
+			varToReduce: "A",
+			vars:        seriesEmpty,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results:     resultValuesNoErr(makeNumber("", nil, NaN)),
+		},
+		{
+			name:        "median series with a nil value",
+			red:         "median",
+			varToReduce: "A",
+			vars:        seriesWithNil,
+			errIs:       require.NoError,
+			resultsIs:   require.Equal,
+			results:     resultValuesNoErr(makeNumber("", nil, NaN)),
+		},
+		{
+			name:        "median series even number of elements",
+			red:         "median",
+			varToReduce: "A",
+			vars: Vars{
+				"A": resultValuesNoErr(
+					makeSeries("temp", nil, tp{
+						time.Unix(5, 0), float64Pointer(20),
+					}, tp{
+						time.Unix(10, 0), float64Pointer(10),
+					}),
+				),
+			},
+			errIs:     require.NoError,
+			resultsIs: require.Equal,
+			results:   resultValuesNoErr(makeNumber("", nil, float64Pointer(15))),
+		},
+		{
+			name:        "median series odd number of elements",
+			red:         "median",
+			varToReduce: "A",
+			vars: Vars{
+				"A": resultValuesNoErr(
+					makeSeries("temp", nil, tp{
+						time.Unix(5, 0), float64Pointer(20),
+					}, tp{
+						time.Unix(10, 0), float64Pointer(10),
+					}, tp{
+						time.Unix(15, 0), float64Pointer(5),
+					}),
+				),
+			},
+			errIs:     require.NoError,
+			resultsIs: require.Equal,
+			results:   resultValuesNoErr(makeNumber("", nil, float64Pointer(10))),
+		},
+		{
+			name:        "median series with repeated values",
+			red:         "median",
+			varToReduce: "A",
+			vars: Vars{
+				"A": resultValuesNoErr(
+					makeSeries("temp", nil, tp{
+						time.Unix(5, 0), float64Pointer(5),
+					}, tp{
+						time.Unix(10, 0), float64Pointer(5),
+					}, tp{
+						time.Unix(15, 0), float64Pointer(5),
+					}),
+				),
+			},
+			errIs:     require.NoError,
+			resultsIs: require.Equal,
+			results:   resultValuesNoErr(makeNumber("", nil, float64Pointer(5))),
+		},
+		{
+			name:        "median series with negative values",
+			red:         "median",
+			varToReduce: "A",
+			vars: Vars{
+				"A": resultValuesNoErr(
+					makeSeries("temp", nil, tp{
+						time.Unix(5, 0), float64Pointer(-1),
+					}, tp{
+						time.Unix(10, 0), float64Pointer(-3),
+					}, tp{
+						time.Unix(10, 0), float64Pointer(-4),
+					}, tp{
+						time.Unix(15, 0), float64Pointer(-2),
+					}),
+				),
+			},
+			errIs:     require.NoError,
+			resultsIs: require.Equal,
+			results:   resultValuesNoErr(makeNumber("", nil, float64Pointer(-2.5))),
+		},
 		{
 			name:        "min series with a nil value",
 			red:         "min",
@@ -257,6 +352,27 @@ func TestSeriesReduceDropNN(t *testing.T) {
 			vars:        seriesEmpty,
 			results:     resultValuesNoErr(makeNumber("", nil, nil)),
 		},
+		{
+			name:        "DropNN: median series with a nil value and real value",
+			red:         "median",
+			varToReduce: "A",
+			vars:        seriesWithNil,
+			results:     resultValuesNoErr(makeNumber("", nil, float64Pointer(2))),
+		},
+		{
+			name:        "DropNN: median empty series",
+			red:         "median",
+			varToReduce: "A",
+			vars:        seriesEmpty,
+			results:     resultValuesNoErr(makeNumber("", nil, nil)),
+		},
+		{
+			name:        "DropNN: median series that becomes empty after filtering non-number",
+			red:         "median",
+			varToReduce: "A",
+			vars:        seriesNonNumbers,
+			results:     resultValuesNoErr(makeNumber("", nil, nil)),
+		},
 		{
 			name:        "DropNN: mean series that becomes empty after filtering non-number",
 			red:         "mean",
@@ -351,6 +467,41 @@ func TestSeriesReduceReplaceNN(t *testing.T) {
 			vars:        seriesNonNumbers,
 			results:     resultValuesNoErr(makeNumber("", nil, float64Pointer(replaceWith))),
 		},
+		{
+			name:        "replaceNN: median series with a nil value and real value",
+			red:         "median",
+			varToReduce: "A",
+			vars: Vars{
+				"A": resultValuesNoErr(
+					makeSeries("temp", nil, tp{
+						time.Unix(5, 0), float64Pointer(2),
+					}, tp{
+						time.Unix(10, 0), nil,
+					}, tp{
+						time.Unix(15, 0), float64Pointer(5),
+					}),
+				),
+			},
+			results: resultValuesNoErr(
+				makeNumber("", nil, float64Pointer(
+					sortedFloat64([]float64{2, 5, replaceWith})[1]),
+				),
+			),
+		},
+		{
+			name:        "replaceNN: median empty series",
+			red:         "median",
+			varToReduce: "A",
+			vars:        seriesEmpty,
+			results:     resultValuesNoErr(makeNumber("", nil, float64Pointer(replaceWith))),
+		},
+		{
+			name:        "replaceNN: median series that becomes empty after filtering non-number",
+			red:         "median",
+			varToReduce: "A",
+			vars:        seriesNonNumbers,
+			results:     resultValuesNoErr(makeNumber("", nil, float64Pointer(replaceWith))),
+		},
 		{
 			name:        "replaceNN: count empty series",
 			red:         "count",
@@ -386,3 +537,9 @@ func TestSeriesReduceReplaceNN(t *testing.T) {
 		})
 	}
 }
+
+func sortedFloat64(f []float64) []float64 {
+	f = append([]float64(nil), f...)
+	sort.Float64s(f)
+	return f
+}

pkg/expr/query.panel.schema.json

@@ -187,7 +187,7 @@
                 "type": "string"
               },
               "reducer": {
-                "description": "The reducer\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` ",
+                "description": "The reducer\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` \n - `\"median\"` ",
                 "type": "string",
                 "enum": [
                   "sum",
@@ -195,7 +195,8 @@
                   "min",
                   "max",
                   "count",
-                  "last"
+                  "last",
+                  "median"
                 ],
                 "x-enum-description": {}
               },
@@ -341,7 +342,7 @@
                 "additionalProperties": false
               },
               "downsampler": {
-                "description": "The downsample function\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` ",
+                "description": "The downsample function\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` \n - `\"median\"` ",
                 "type": "string",
                 "enum": [
                   "sum",
@@ -349,7 +350,8 @@
                   "min",
                   "max",
                   "count",
-                  "last"
+                  "last",
+                  "median"
                 ],
                 "x-enum-description": {}
               },

pkg/expr/query.request.schema.json

@@ -213,7 +213,7 @@
                 "type": "string"
               },
               "reducer": {
-                "description": "The reducer\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` ",
+                "description": "The reducer\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` \n - `\"median\"` ",
                 "type": "string",
                 "enum": [
                   "sum",
@@ -221,7 +221,8 @@
                   "min",
                   "max",
                   "count",
-                  "last"
+                  "last",
+                  "median"
                 ],
                 "x-enum-description": {}
               },
@@ -367,7 +368,7 @@
                 "additionalProperties": false
               },
               "downsampler": {
-                "description": "The downsample function\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` ",
+                "description": "The downsample function\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` \n - `\"median\"` ",
                 "type": "string",
                 "enum": [
                   "sum",
@@ -375,7 +376,8 @@
                   "min",
                   "max",
                   "count",
-                  "last"
+                  "last",
+                  "median"
                 ],
                 "x-enum-description": {}
               },

pkg/expr/query.types.json

@@ -56,7 +56,7 @@
     {
       "metadata": {
         "name": "reduce",
-        "resourceVersion": "1709915979242",
+        "resourceVersion": "1722250145266",
         "creationTimestamp": "2024-02-21T22:09:26Z"
       },
       "spec": {
@@ -79,14 +79,15 @@
               "type": "string"
             },
             "reducer": {
-              "description": "The reducer\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` ",
+              "description": "The reducer\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` \n - `\"median\"` ",
               "enum": [
                 "sum",
                 "mean",
                 "min",
                 "max",
                 "count",
-                "last"
+                "last",
+                "median"
               ],
               "type": "string",
               "x-enum-description": {}
@@ -141,7 +142,7 @@
     {
       "metadata": {
         "name": "resample",
-        "resourceVersion": "1709915973363",
+        "resourceVersion": "1722250145266",
         "creationTimestamp": "2024-02-21T22:09:26Z"
       },
       "spec": {
@@ -157,14 +158,15 @@
           "description": "QueryType = resample",
           "properties": {
             "downsampler": {
-              "description": "The downsample function\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` ",
+              "description": "The downsample function\n\n\nPossible enum values:\n - `\"sum\"` \n - `\"mean\"` \n - `\"min\"` \n - `\"max\"` \n - `\"count\"` \n - `\"last\"` \n - `\"median\"` ",
               "enum": [
                 "sum",
                 "mean",
                 "min",
                 "max",
                 "count",
-                "last"
+                "last",
+                "median"
               ],
               "type": "string",
               "x-enum-description": {}

public/api-enterprise-spec.json

@@ -4806,6 +4806,7 @@
             "PENDING_PROCESSING",
             "PROCESSING",
             "FINISHED",
+            "CANCELED",
             "ERROR",
             "UNKNOWN"
           ]
@@ -5490,7 +5491,7 @@
       "type": "object",
       "title": "NavbarPreference defines model for NavbarPreference.",
       "properties": {
-        "savedItemIds": {
+        "bookmarkIds": {
           "type": "array",
           "items": {
             "type": "string"
@@ -7217,6 +7218,7 @@
             "PENDING_PROCESSING",
             "PROCESSING",
             "FINISHED",
+            "CANCELED",
             "ERROR",
             "UNKNOWN"
           ]
@@ -7247,6 +7249,10 @@
             "format": "int64"
           }
         },
+        "total": {
+          "type": "integer",
+          "format": "int64"
+        },
         "types": {
           "type": "object",
           "additionalProperties": {
@@ -8380,6 +8386,23 @@
         }
       }
     },
+    "healthResponse": {
+      "type": "object",
+      "properties": {
+        "commit": {
+          "type": "string"
+        },
+        "database": {
+          "type": "string"
+        },
+        "enterpriseCommit": {
+          "type": "string"
+        },
+        "version": {
+          "type": "string"
+        }
+      }
+    },
     "publicError": {
       "description": "PublicError is derived from Error and only contains information\navailable to the end user.",
       "type": "object",

public/app/features/expressions/types.ts

@@ -79,6 +79,7 @@ export const reducerTypes: Array<SelectableValue<string>> = [
   { value: ReducerID.min, label: 'Min', description: 'Get the minimum value' },
   { value: ReducerID.max, label: 'Max', description: 'Get the maximum value' },
   { value: ReducerID.mean, label: 'Mean', description: 'Get the average value' },
+  { value: ReducerID.median, label: 'Median', description: 'Get the median value' },
   { value: ReducerID.sum, label: 'Sum', description: 'Get the sum of all values' },
   { value: ReducerID.count, label: 'Count', description: 'Get the number of values' },
   { value: ReducerID.last, label: 'Last', description: 'Get the last value' },