Merge c1ce72e into af3269f

plotter/histogram.go

@@ -150,7 +150,7 @@ func (h *Histogram) Thumbnail(c *draw.Canvas) {
 // then a reasonable default is used.  The
 // default is the square root of the sum of
 // the y values.
-func binPoints(xys XYer, n int) ([]HistogramBin, float64) {
+func binPoints(xys XYer, n int) (bins []HistogramBin, width float64) {
 	xmin, xmax := Range(XValues{xys})
 	if n <= 0 {
 		m := 0.0
@@ -164,9 +164,12 @@ func binPoints(xys XYer, n int) ([]HistogramBin, float64) {
 		n = 1
 	}
 
-	bins := make([]HistogramBin, n)
+	bins = make([]HistogramBin, n)
 
 	w := (xmax - xmin) / float64(n)
+	if w == 0 {
+		w = 1
+	}
 	for i := range bins {
 		bins[i].Min = xmin + float64(i)*w
 		bins[i].Max = xmin + float64(i+1)*w

plotter/histogram_test.go

@@ -10,6 +10,7 @@ import (
 	"math"
 	"math/rand"
 	"testing"
+	"time"
 
 	"gonum.org/v1/plot"
 	"gonum.org/v1/plot/internal/cmpimg"
@@ -62,3 +63,33 @@ func ExampleHistogram() {
 func TestHistogram(t *testing.T) {
 	cmpimg.CheckPlot(ExampleHistogram, t, "histogram.png")
 }
+
+func TestSingletonHistogram(t *testing.T) {
+	done := make(chan struct{}, 1)
+	go func() {
+		defer close(done)
+		p, err := plot.New()
+		if err != nil {
+			t.Fatalf("unexpected error from plot.New: %v", err)
+		}
+
+		hist, err := NewHist(Values([]float64{1.0}), 60)
+		if err != nil {
+			t.Fatalf("unexpected error from NewHist: %v", err)
+		}
+		hist.Normalize(1)
+
+		p.Add(hist)
+
+		_, err = p.WriterTo(4*vg.Inch, 4*vg.Inch, "png")
+		if err != nil {
+			t.Fatalf("unexpected error from WriterTo: %v", err)
+		}
+	}()
+
+	select {
+	case <-time.After(10 * time.Second):
+		t.Error("histogram timed out")
+	case <-done:
+	}
+}