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logisticModel.go
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logisticModel.go
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package library
import (
"errors"
"github.com/nytlabs/gojee" // jee
"github.com/nytlabs/streamtools/st/blocks" // blocks
"github.com/nytlabs/streamtools/st/util" // util
"math"
"math/rand"
)
// specify those channels we're going to use to communicate with streamtools
type LogisticModel struct {
blocks.Block
queryrule chan chan interface{}
inrule chan interface{}
in chan interface{}
out chan interface{}
quit chan interface{}
}
// we need to build a simple factory so that streamtools can make new blocks of this kind
func NewLogisticModel() blocks.BlockInterface {
return &LogisticModel{}
}
// Setup is called once before running the block. We build up the channels and specify what kind of block this is.
func (b *LogisticModel) Setup() {
b.Kind = "LogisticModel"
b.Desc = "returns 1 or 0 depending on the model parameters and feature values"
b.inrule = b.InRoute("rule")
b.queryrule = b.QueryRoute("rule")
b.in = b.InRoute("in")
b.quit = b.Quit()
b.out = b.Broadcast()
}
func logit(x float64) float64 {
return 1 / (1 + math.Exp(-x))
}
// Run is the block's main loop. Here we listen on the different channels we set up.
func (b *LogisticModel) Run() {
var β []float64
var featurePaths []string
var featureTrees []*jee.TokenTree
var err error
for {
Loop:
select {
case rule := <-b.inrule:
β, err = util.ParseArrayFloat(rule, "Weights")
if err != nil {
b.Error(err)
continue
}
featurePaths, err = util.ParseArrayString(rule, "FeaturePaths")
if err != nil {
b.Error(err)
continue
}
featureTrees = make([]*jee.TokenTree, len(featurePaths))
for i, path := range featurePaths {
token, err := jee.Lexer(path)
if err != nil {
b.Error(err)
break
}
tree, err := jee.Parser(token)
if err != nil {
b.Error(err)
break
}
featureTrees[i] = tree
}
case <-b.quit:
// quit the block
return
case msg := <-b.in:
if featureTrees == nil {
continue
}
x := make([]float64, len(featureTrees))
for i, tree := range featureTrees {
feature, err := jee.Eval(tree, msg)
if err != nil {
b.Error(err)
break Loop
}
fi, ok := feature.(float64)
if !ok {
b.Error(errors.New("features must be float64"))
break Loop
}
x[i] = fi
}
μ := 0.0
for i, βi := range β {
μ += βi * x[i]
}
var y float64
if rand.Float64() <= logit(μ) {
y = 1
} else {
y = 0
}
b.out <- map[string]interface{}{
"Response": y,
}
case respChan := <-b.queryrule:
// deal with a query request
out := map[string]interface{}{
"Weights": β,
"FeaturePaths": featurePaths,
}
respChan <- out
}
}
}