github.com/go-graphite/carbonapi@v0.17.0/expr/functions/holtWintersForecast/function.go (about)

     1  package holtWintersForecast
     2  
     3  import (
     4  	"context"
     5  
     6  	"github.com/go-graphite/carbonapi/expr/helper"
     7  	"github.com/go-graphite/carbonapi/expr/holtwinters"
     8  	"github.com/go-graphite/carbonapi/expr/interfaces"
     9  	"github.com/go-graphite/carbonapi/expr/types"
    10  	"github.com/go-graphite/carbonapi/pkg/parser"
    11  	pb "github.com/go-graphite/protocol/carbonapi_v3_pb"
    12  )
    13  
    14  type holtWintersForecast struct{}
    15  
    16  func GetOrder() interfaces.Order {
    17  	return interfaces.Any
    18  }
    19  
    20  func New(configFile string) []interfaces.FunctionMetadata {
    21  	res := make([]interfaces.FunctionMetadata, 0)
    22  	f := &holtWintersForecast{}
    23  	functions := []string{"holtWintersForecast"}
    24  	for _, n := range functions {
    25  		res = append(res, interfaces.FunctionMetadata{Name: n, F: f})
    26  	}
    27  	return res
    28  }
    29  
    30  func (f *holtWintersForecast) Do(ctx context.Context, eval interfaces.Evaluator, e parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) ([]*types.MetricData, error) {
    31  	bootstrapInterval, err := e.GetIntervalNamedOrPosArgDefault("bootstrapInterval", 1, 1, holtwinters.DefaultBootstrapInterval)
    32  	if err != nil {
    33  		return nil, err
    34  	}
    35  
    36  	args, err := helper.GetSeriesArg(ctx, eval, e.Arg(0), from-bootstrapInterval, until, values)
    37  	if err != nil {
    38  		return nil, err
    39  	}
    40  
    41  	seasonality, err := e.GetIntervalNamedOrPosArgDefault("seasonality", 2, 1, holtwinters.DefaultSeasonality)
    42  	if err != nil {
    43  		return nil, err
    44  	}
    45  
    46  	var predictionsOfInterest []float64
    47  	results := make([]*types.MetricData, len(args))
    48  	for i, arg := range args {
    49  		stepTime := arg.StepTime
    50  
    51  		predictions, _ := holtwinters.HoltWintersAnalysis(arg.Values, stepTime, seasonality)
    52  
    53  		windowPoints := int(bootstrapInterval / stepTime)
    54  		if len(predictions) < windowPoints {
    55  			predictionsOfInterest = predictions
    56  		} else {
    57  			predictionsOfInterest = predictions[windowPoints:]
    58  		}
    59  
    60  		name := "holtWintersForecast(" + arg.Name + ")"
    61  		r := &types.MetricData{
    62  			FetchResponse: pb.FetchResponse{
    63  				Name:              name,
    64  				Values:            predictionsOfInterest,
    65  				StepTime:          arg.StepTime,
    66  				StartTime:         arg.StartTime + bootstrapInterval,
    67  				StopTime:          arg.StopTime,
    68  				PathExpression:    name,
    69  				XFilesFactor:      arg.XFilesFactor,
    70  				ConsolidationFunc: arg.ConsolidationFunc,
    71  			},
    72  			Tags: helper.CopyTags(arg),
    73  		}
    74  		r.Tags["holtWintersForecast"] = "1"
    75  		results[i] = r
    76  	}
    77  	return results, nil
    78  }
    79  
    80  // Description is auto-generated description, based on output of https://github.com/graphite-project/graphite-web
    81  func (f *holtWintersForecast) Description() map[string]types.FunctionDescription {
    82  	return map[string]types.FunctionDescription{
    83  		"holtWintersForecast": {
    84  			Description: "Performs a Holt-Winters forecast using the series as input data. Data from\n`bootstrapInterval` (one week by default) previous to the series is used to bootstrap the initial forecast.",
    85  			Function:    "holtWintersForecast(seriesList, bootstrapInterval='7d')",
    86  			Group:       "Calculate",
    87  			Module:      "graphite.render.functions",
    88  			Name:        "holtWintersForecast",
    89  			Params: []types.FunctionParam{
    90  				{
    91  					Name:     "seriesList",
    92  					Required: true,
    93  					Type:     types.SeriesList,
    94  				},
    95  				{
    96  					Default: types.NewSuggestion("7d"),
    97  					Name:    "bootstrapInterval",
    98  					Suggestions: types.NewSuggestions(
    99  						"7d",
   100  						"30d",
   101  					),
   102  					Type: types.Interval,
   103  				},
   104  			},
   105  			NameChange:   true, // name changed
   106  			TagsChange:   true, // name tag changed
   107  			ValuesChange: true, // values changed
   108  		},
   109  	}
   110  }