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

     1  package exp
     2  
     3  import (
     4  	"context"
     5  	"math"
     6  
     7  	"github.com/go-graphite/carbonapi/expr/helper"
     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  )
    12  
    13  type exp struct{}
    14  
    15  // offset(seriesList,factor)
    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 := &exp{}
    23  	for _, n := range []string{"exp"} {
    24  		res = append(res, interfaces.FunctionMetadata{Name: n, F: f})
    25  	}
    26  	return res
    27  }
    28  
    29  func (f *exp) Do(ctx context.Context, eval interfaces.Evaluator, e parser.Expr, from, until int64, values map[parser.MetricRequest][]*types.MetricData) ([]*types.MetricData, error) {
    30  	args, err := helper.GetSeriesArg(ctx, eval, e.Arg(0), from, until, values)
    31  	if err != nil {
    32  		return nil, err
    33  	}
    34  	var results []*types.MetricData
    35  
    36  	for _, a := range args {
    37  		r := a.CopyLink()
    38  		r.Name = "exp(" + a.Name + ")"
    39  		r.Values = make([]float64, len(a.Values))
    40  		r.Tags["exp"] = "e"
    41  
    42  		for i, v := range a.Values {
    43  			if math.IsNaN(v) {
    44  				r.Values[i] = math.NaN()
    45  			} else {
    46  				r.Values[i] = math.Exp(v)
    47  			}
    48  		}
    49  		results = append(results, r)
    50  	}
    51  	return results, nil
    52  }
    53  
    54  // Description is auto-generated description, based on output of https://github.com/graphite-project/graphite-web
    55  func (f *exp) Description() map[string]types.FunctionDescription {
    56  	return map[string]types.FunctionDescription{
    57  		"exp": {
    58  			Description: "Raise e to the power of the datapoint, where e = 2.718281… is the base of natural logarithms.\n\nExample:\n\n.. code-block:: none\n\n  &target=exp(Server.instance01.threads.busy)",
    59  			Function:    "exp(seriesList)",
    60  			Group:       "Transform",
    61  			Module:      "graphite.render.functions",
    62  			Name:        "exp",
    63  			Params: []types.FunctionParam{
    64  				{
    65  					Name:     "seriesList",
    66  					Required: true,
    67  					Type:     types.SeriesList,
    68  				},
    69  			},
    70  		},
    71  	}
    72  }