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Align time series data if possible

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This commit is contained in:
Alexander Zobnin
2021-05-31 17:42:24 +03:00
parent 4f7699442e
commit 7d5b7cad3e
8 changed files with 99 additions and 109 deletions
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52
pkg/timeseries/align.go Normal file
View File

@@ -0,0 +1,52 @@
package timeseries
import (
"math"
"sort"
"time"
)
// Aligns point's time stamps according to provided interval.
func (ts TimeSeries) Align(interval time.Duration) TimeSeries {
if interval <= 0 || ts.Len() < 2 {
return ts
}
alignedTs := NewTimeSeries()
var frameTs = ts[0].GetTimeFrame(interval)
var pointFrameTs time.Time
var point TimePoint
for i := 0; i < ts.Len(); i++ {
point = ts[i]
pointFrameTs = point.GetTimeFrame(interval)
if pointFrameTs.After(frameTs) {
for frameTs.Before(pointFrameTs) {
alignedTs = append(alignedTs, TimePoint{Time: frameTs, Value: nil})
frameTs = frameTs.Add(interval)
}
}
alignedTs = append(alignedTs, TimePoint{Time: pointFrameTs, Value: point.Value})
frameTs = frameTs.Add(interval)
}
return alignedTs
}
// Detects interval between data points in milliseconds based on median delta between points.
func (ts TimeSeries) DetectInterval() time.Duration {
if ts.Len() < 2 {
return 0
}
deltas := make([]int, 0)
for i := 1; i < ts.Len(); i++ {
delta := ts[i].Time.Sub(ts[i-1].Time)
deltas = append(deltas, int(delta.Milliseconds()))
}
sort.Ints(deltas)
midIndex := int(math.Floor(float64(len(deltas)) * 0.5))
return time.Duration(deltas[midIndex]) * time.Millisecond
}

3
pkg/timeseries/models.go
View File

@@ -29,6 +29,9 @@ type TimeSeriesData struct {
type TimeSeriesMeta struct {
Name string
Item *zabbix.Item
// Item update interval. nil means not supported intervals (flexible, schedule, etc)
Interval *time.Duration
}
type AggFunc = func(points []TimePoint) *float64

99
pkg/timeseries/timeseries.go
View File

@@ -1,12 +1,9 @@
package timeseries
import (
"errors"
"math"
"sort"
"time"
"github.com/grafana/grafana-plugin-sdk-go/backend"
"github.com/grafana/grafana-plugin-sdk-go/data"
)
@@ -286,94 +283,11 @@ func findNearestLeft(series TimeSeries, pointIndex int) *TimePoint {
return nil
}
// Aligns point's time stamps according to provided interval.
func (ts TimeSeries) Align(interval time.Duration) TimeSeries {
if interval <= 0 || ts.Len() < 2 {
return ts
}
alignedTs := NewTimeSeries()
var frameTs = ts[0].GetTimeFrame(interval)
var pointFrameTs time.Time
var point TimePoint
for i := 1; i < ts.Len(); i++ {
point = ts[i]
pointFrameTs = point.GetTimeFrame(interval)
if pointFrameTs.After(frameTs) {
for frameTs.Before(pointFrameTs) {
alignedTs = append(alignedTs, TimePoint{Time: frameTs, Value: nil})
frameTs = frameTs.Add(interval)
}
}
alignedTs = append(alignedTs, TimePoint{Time: pointFrameTs, Value: point.Value})
frameTs = frameTs.Add(interval)
}
return alignedTs
}
// Detects interval between data points in milliseconds based on median delta between points.
func (ts TimeSeries) DetectInterval() time.Duration {
if ts.Len() < 2 {
return 0
}
deltas := make([]int, 0)
for i := 1; i < ts.Len(); i++ {
delta := ts[i].Time.Sub(ts[i-1].Time)
deltas = append(deltas, int(delta.Milliseconds()))
}
sort.Ints(deltas)
midIndex := int(math.Floor(float64(len(deltas)) * 0.5))
return time.Duration(deltas[midIndex]) * time.Millisecond
}
// Gets point timestamp rounded according to provided interval.
func (p *TimePoint) GetTimeFrame(interval time.Duration) time.Time {
return p.Time.Truncate(interval)
}
func alignDataPoints(frame *data.Frame, interval time.Duration) *data.Frame {
if interval <= 0 || frame.Rows() < 2 {
return frame
}
timeFieldIdx := getTimeFieldIndex(frame)
if timeFieldIdx < 0 {
return frame
}
var frameTs = getPointTimeFrame(getTimestampAt(frame, 0), interval)
var pointFrameTs *time.Time
var pointsInserted = 0
for i := 1; i < frame.Rows(); i++ {
pointFrameTs = getPointTimeFrame(getTimestampAt(frame, i), interval)
if pointFrameTs == nil || frameTs == nil {
continue
}
if pointFrameTs.After(*frameTs) {
for frameTs.Before(*pointFrameTs) {
insertAt := i + pointsInserted
err := insertNullPointAt(frame, *frameTs, insertAt)
if err != nil {
backend.Logger.Debug("Error inserting null point", "error", err)
}
*frameTs = frameTs.Add(interval)
pointsInserted++
}
}
setTimeAt(frame, *pointFrameTs, i+pointsInserted)
*frameTs = frameTs.Add(interval)
}
return frame
}
func getPointTimeFrame(ts *time.Time, interval time.Duration) *time.Time {
if ts == nil {
return nil
@@ -407,19 +321,6 @@ func getTimestampAt(frame *data.Frame, index int) *time.Time {
return &ts
}
func insertNullPointAt(frame *data.Frame, frameTs time.Time, index int) error {
for _, field := range frame.Fields {
if field.Type() == data.FieldTypeTime {
field.Insert(index, frameTs)
} else if field.Type().Nullable() {
field.Insert(index, nil)
} else {
return errors.New("field is not nullable")
}
}
return nil
}
func setTimeAt(frame *data.Frame, frameTs time.Time, index int) {
for _, field := range frame.Fields {
if field.Type() == data.FieldTypeTime {