added gonum stat library, moved plotResults to test file

go.mod

@@ -14,6 +14,7 @@ require (
 	github.com/pkg/errors v0.9.1
 	github.com/yobert/alsa v0.0.0-20180630182551-d38d89fa843e
 	gocv.io/x/gocv v0.29.0
+	gonum.org/v1/gonum v0.9.3
 	gonum.org/v1/plot v0.10.0
 	gopkg.in/natefinch/lumberjack.v2 v2.0.0
 )

go.sum

@@ -58,10 +58,8 @@ github.com/jung-kurt/gofpdf v1.0.0/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+
 github.com/jung-kurt/gofpdf v1.0.3-0.20190309125859-24315acbbda5/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+r32jIOes=
 github.com/kidoman/embd v0.0.0-20170508013040-d3d8c0c5c68d h1:dPUSr0RGzXAdsUTMtiyQ/2RBLIIwkv6jGnhxrufitvQ=
 github.com/kidoman/embd v0.0.0-20170508013040-d3d8c0c5c68d/go.mod h1:ACKj9jnzOzj1lw2ETilpFGK7L9dtJhAzT7T1OhAGtRQ=
-github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
-github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/mattetti/audio v0.0.0-20180912171649-01576cde1f21 h1:Hc1iKlyxNHp3CV59G2E/qabUkHvEwOIJxDK0CJ7CRjA=
 github.com/mattetti/audio v0.0.0-20180912171649-01576cde1f21/go.mod h1:LlQmBGkOuV/SKzEDXBPKauvN2UqCgzXO2XjecTGj40s=
@@ -149,7 +147,6 @@ gonum.org/v1/plot v0.9.0/go.mod h1:3Pcqqmp6RHvJI72kgb8fThyUnav364FOsdDo2aGW5lY=
 gonum.org/v1/plot v0.10.0 h1:ymLukg4XJlQnYUJCp+coQq5M7BsUJFk6XQE4HPflwdw=
 gonum.org/v1/plot v0.10.0/go.mod h1:JWIHJ7U20drSQb/aDpTetJzfC1KlAPldJLpkSy88dvQ=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/natefinch/lumberjack.v2 v2.0.0 h1:1Lc07Kr7qY4U2YPouBjpCLxpiyxIVoxqXgkXLknAOE8=
 gopkg.in/natefinch/lumberjack.v2 v2.0.0/go.mod h1:l0ndWWf7gzL7RNwBG7wST/UCcT4T24xpD6X8LsfU/+k=

turbidity/plot.go

@@ -30,74 +30,35 @@ import (
 
 	"gonum.org/v1/plot"
 	"gonum.org/v1/plot/plotter"
-	"gonum.org/v1/plot/plotutil"
 	"gonum.org/v1/plot/vg"
 )
 
-// standarDeviation will return the standard deviation of a float slice
-func standarDeviation(slice []float64) float64 {
-	mean := average(slice)
-	variance := 0.0
-
-	for _, i := range slice {
-		variance += math.Pow(i-mean, 2.0)
-	}
-	return math.Sqrt(variance / float64(len(slice)))
-}
-
-// Normalize values in a slice between 0 and 1.
-func normalize(slice []float64) []float64 {
+// normalise normalises the values in the given slice to the range [0,1] inclusive.
+func normalize(s []float64) []float64 {
 	max := -math.MaxFloat64
 	min := math.MaxFloat64
-	out := make([]float64, len(slice))
+	out := make([]float64, len(s))
 
-	if len(slice) <= 1 {
-		return slice
+	if len(s) <= 1 {
+		return s
 	}
 
-	// Find the max and min values of the slice.
-	for i := range slice {
-		if slice[i] > max {
-			max = slice[i]
+	// Find the max and min values of the s.
+	for i := range s {
+		if s[i] > max {
+			max = s[i]
 		}
-		if slice[i] < min {
-			min = slice[i]
+		if s[i] < min {
+			min = s[i]
 		}
 	}
 
-	for i := range slice {
-		out[i] = (slice[i] - min) / (max - min)
+	for i := range s {
+		out[i] = (s[i] - min) / (max - min)
 	}
 	return out
 }
 
-// Return the average of a slice.
-func average(slice []float64) float64 {
-	var out float64
-	for i := range slice {
-		out += slice[i]
-	}
-	return out / float64(len(slice))
-}
-
-func plotResults(x, sharpness, contrast []float64) error {
-	err := plotToFile(
-		"Results",
-		"Almond Milk (ml)",
-		"Score",
-		func(p *plot.Plot) error {
-			return plotutil.AddLinePoints(p,
-				"Contrast", plotterXY(x, contrast),
-				"Sharpness", plotterXY(x, sharpness),
-			)
-		},
-	)
-	if err != nil {
-		return fmt.Errorf("Could not plot results: %w", err)
-	}
-	return nil
-}
-
 // plotToFile creates a plot with a specified name and x&y titles using the
 // provided draw function, and then saves to a PNG file with filename of name.
 func plotToFile(name, xTitle, yTitle string, draw func(*plot.Plot) error) error {

turbidity/results.go

@@ -36,7 +36,7 @@ type Results struct {
 	Contrast  []float64
 }
 
-// NewResults returns a new Results
+// NewResults returns a new Results.
 func NewResults(n int) (*Results, error) {
 	if n <= 0 {
 		return nil, fmt.Errorf("invalid result size: %v", n)

turbidity/turbidity_test.go

@@ -30,12 +30,15 @@ import (
 	"testing"
 
 	"gocv.io/x/gocv"
+	"gonum.org/v1/gonum/stat"
+	"gonum.org/v1/plot"
+	"gonum.org/v1/plot/plotutil"
 )
 
 const (
 	nImages   = 13  // Number of images to test. (Max 13)
 	nSamples  = 10  // Number of samples for each image. (Max 10)
-	increment = 2.5 // Increment of the turbidity level
+	increment = 2.5 // Increment of the turbidity level.
 )
 
 func TestImages(t *testing.T) {
@@ -45,7 +48,6 @@ func TestImages(t *testing.T) {
 		scale, alpha = 1.0, 1.0
 	)
 
-	// Load template and standard image.
 	template := gocv.IMRead("images/template.jpg", gocv.IMReadGrayScale)
 	standard := gocv.IMRead("images/default.jpg", gocv.IMReadGrayScale)
 
@@ -59,13 +61,11 @@ func TestImages(t *testing.T) {
 		}
 	}
 
-	// Create turbidity sensor.
 	ts, err := NewTurbiditySensor(template, standard, k1, k2, filterSize, scale, alpha)
 	if err != nil {
 		t.Fatal("could not create turbidity sensor: %w", err)
 	}
 
-	// Create results.
 	results, err := NewResults(nImages)
 	if err != nil {
 		t.Fatal("could not create results: %w", err)
@@ -80,10 +80,9 @@ func TestImages(t *testing.T) {
 		}
 
 		// Add the average result from camera burst.
-		results.Update(average(sample_result.Sharpness), average(sample_result.Contrast), float64(i)*increment, i)
+		results.Update(stat.Mean(sample_result.Sharpness, nil), stat.Mean(sample_result.Contrast, nil), float64(i)*increment, i)
 	}
 
-	// Plot the final results.
 	err = plotResults(results.Turbidity, normalize(results.Sharpness), normalize(results.Contrast))
 	if err != nil {
 		t.Fatalf("plotting Failed: %v", err)
@@ -92,3 +91,21 @@ func TestImages(t *testing.T) {
 	t.Logf("Sharpness: %v", results.Sharpness)
 	t.Logf("Contrast: %v", results.Contrast)
 }
+
+func plotResults(x, sharpness, contrast []float64) error {
+	err := plotToFile(
+		"Results",
+		"Almond Milk (ml)",
+		"Score",
+		func(p *plot.Plot) error {
+			return plotutil.AddLinePoints(p,
+				"Contrast", plotterXY(x, contrast),
+				"Sharpness", plotterXY(x, sharpness),
+			)
+		},
+	)
+	if err != nil {
+		return fmt.Errorf("Could not plot results: %w", err)
+	}
+	return nil
+}