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

     1  package logit
     2  
     3  import (
     4  	"context"
     5  	"fmt"
     6  	"math"
     7  
     8  	"github.com/go-graphite/carbonapi/expr/helper"
     9  	"github.com/go-graphite/carbonapi/expr/interfaces"
    10  	"github.com/go-graphite/carbonapi/expr/types"
    11  	"github.com/go-graphite/carbonapi/pkg/parser"
    12  )
    13  
    14  type logit 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 := &logit{}
    23  	functions := []string{"logit"}
    24  	for _, n := range functions {
    25  		res = append(res, interfaces.FunctionMetadata{Name: n, F: f})
    26  	}
    27  	return res
    28  }
    29  
    30  // logarithm(seriesList, base=10)
    31  // Alias: log
    32  func (f *logit) Do(ctx context.Context, eval interfaces.Evaluator, e parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) ([]*types.MetricData, error) {
    33  	arg, err := helper.GetSeriesArg(ctx, eval, e.Arg(0), from, until, values)
    34  	if err != nil {
    35  		return nil, err
    36  	}
    37  
    38  	var results []*types.MetricData
    39  	for _, a := range arg {
    40  		r := a.CopyLink()
    41  		r.Name = fmt.Sprintf("logit(%s)", a.Name)
    42  		r.Values = make([]float64, len(a.Values))
    43  		r.Tags["logit"] = "logit"
    44  
    45  		for i, v := range a.Values {
    46  			if math.IsNaN(v) || v == 1 {
    47  				r.Values[i] = math.NaN()
    48  			} else {
    49  				r.Values[i] = math.Log(v / (1 - v))
    50  			}
    51  		}
    52  		results = append(results, r)
    53  	}
    54  	return results, nil
    55  }
    56  
    57  // Description is auto-generated description, based on output of https://github.com/graphite-project/graphite-web
    58  func (f *logit) Description() map[string]types.FunctionDescription {
    59  	return map[string]types.FunctionDescription{
    60  		"logit": {
    61  			Description: "Takes one metric or a wildcard seriesList and applies the logit function log(x / (1 - x)) to each datapoint.\n\nExample:\n\n.. code-block:: none\n\n  &target=logit(Server.instance01.threads.busy)\n&target=logit(Server.instance*.threads.busy)",
    62  			Function:    "logit(seriesList)",
    63  			Group:       "Transform",
    64  			Module:      "graphite.render.functions",
    65  			Name:        "logit",
    66  			Params: []types.FunctionParam{
    67  				{
    68  					Name:     "seriesList",
    69  					Required: true,
    70  					Type:     types.SeriesList,
    71  				},
    72  			},
    73  		},
    74  	}
    75  }