fix: bad inference result conversion

pkg/steering/steering.go

@@ -7,6 +7,7 @@ import (
 	"github.com/cyrilix/robocar-base/service"
 	"github.com/cyrilix/robocar-protobuf/go/events"
 	"github.com/cyrilix/robocar-steering-tflite-edgetpu/pkg/metrics"
+	"github.com/cyrilix/robocar-steering-tflite-edgetpu/pkg/tools"
 	"github.com/disintegration/imaging"
 	mqtt "github.com/eclipse/paho.mqtt.golang"
 	"github.com/golang/protobuf/proto"
@@ -15,7 +16,6 @@ import (
 	"go.uber.org/zap"
 	"image"
 	_ "image/jpeg"
-	"sort"
 	"time"
 )
 
@@ -212,43 +212,21 @@ func (p *Part) Value(img image.Image) (float32, float32, error) {
 	}
 
 	output := p.interpreter.GetOutputTensor(0)
+
 	outputSize := output.Dim(output.NumDims() - 1)
+
 	b := make([]byte, outputSize)
-	type result struct {
-		score float64
-		index int
-	}
 	status = output.CopyToBuffer(&b[0])
 	if status != tflite.OK {
 		return 0., 0., fmt.Errorf("output failed: %v", status)
 	}
 
-	var results []result
+	steering, score := tools.LinearBin(b, 15, -1, 2.0)
-	minScore := 0.2
-	for i := 0; i < outputSize; i++ {
-		score := float64(b[i]) / 255.0
-		if score < minScore {
-			continue
-		}
-		results = append(results, result{score: score, index: i})
-	}
-
-	if len(results) == 0 {
-		zap.L().Warn(fmt.Sprintf("none steering with score > %0.2f found", minScore))
-		return 0., 0., nil
-	}
-	zap.S().Debugf("raw result: %v", results)
-
-	sort.Slice(results, func(i, j int) bool {
-		return results[i].score > results[j].score
-	})
-
-	steering := float64(results[0].index)*(2./float64(outputSize)) - 1
 	zap.L().Debug("found steering",
 		zap.Float64("steering", steering),
-		zap.Float64("score", results[0].score),
+		zap.Float64("score", score),
 	)
-	return float32(steering), float32(results[0].score), nil
+	return float32(steering), float32(score), nil
 }
 
 var registerCallbacks = func(p *Part) error {

pkg/tools/tools.go

@@ -0,0 +1,40 @@
+package tools
+
+import (
+	"fmt"
+	"go.uber.org/zap"
+	"sort"
+)
+
+// LinearBin  perform inverse linear_bin, taking
+func LinearBin(arr []byte, n int, offset int, r float64) (float64, float64) {
+	outputSize := len(arr)
+	type result struct {
+		score float64
+		index int
+	}
+
+	var results []result
+	minScore := 0.2
+	for i := 0; i < outputSize; i++ {
+		score := float64(arr[i]) / 255.0
+		if score < minScore {
+			continue
+		}
+		results = append(results, result{score: score, index: i})
+	}
+
+	if len(results) == 0 {
+		zap.L().Warn(fmt.Sprintf("none steering with score > %0.2f found", minScore))
+		return 0., 0.
+	}
+	zap.S().Debugf("raw result: %v", results)
+
+	sort.Slice(results, func(i, j int) bool {
+		return results[i].score > results[j].score
+	})
+
+	b := results[0].index
+	a := float64(b)*(r/(float64(n)+float64(offset))) + float64(offset)
+	return a, results[0].score
+}

pkg/tools/tools_test.go

@@ -0,0 +1,77 @@
+package tools
+
+import (
+	"testing"
+)
+
+func Test_LinearBin(t *testing.T) {
+	type args struct {
+		arr    []byte
+		n      int
+		offset int
+		r      float64
+	}
+	tests := []struct {
+		name  string
+		args  args
+		want  float64
+		want1 float64
+	}{
+		{
+			name: "default",
+			args: args{
+				arr:    []byte{0, 0, 0, 0, 0, 0, 0, 255, 0, 0, 0, 0, 0, 0, 0},
+				n:      15,
+				offset: -1,
+				r:      2.0,
+			},
+			want:  0.,
+			want1: 1.0,
+		},
+		{
+			name: "left",
+			args: args{
+				arr:    []byte{255, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
+				n:      15,
+				offset: -1,
+				r:      2.0,
+			},
+			want:  -1.,
+			want1: 1.0,
+		},
+		{
+			name: "right",
+			args: args{
+				arr:    []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255},
+				n:      15,
+				offset: -1,
+				r:      2.0,
+			},
+			want:  1.,
+			want1: 1.0,
+		},
+		{
+			name: "right",
+			args: args{
+				arr:    []byte{0, 0, 0, 0, 0, 0, 0, 5, 10, 15, 20, 40, 100, 60, 5},
+				n:      15,
+				offset: -1,
+				r:      2.0,
+			},
+			want:  0.7142857142857142,
+			want1: 0.39215686274509803,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got1 := LinearBin(tt.args.arr, tt.args.n, tt.args.offset, tt.args.r)
+			if got != tt.want {
+				t.Errorf("linearBin() got = %v, want %v", got, tt.want)
+			}
+			if got1 != tt.want1 {
+				t.Errorf("linearBin() got1 = %v, want %v", got1, tt.want1)
+			}
+		})
+	}
+}