fixed dependencies

vendor/gonum.org/v1/plot/palette/reverse.go

@@ -0,0 +1,35 @@
+// Copyright ©2017 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package palette
+
+import (
+	"image/color"
+)
+
+// Reverse reverses the direction of ColorMap c.
+func Reverse(c ColorMap) ColorMap {
+	return reverse{ColorMap: c}
+}
+
+// reverse is a ColorMap that reverses the direction of the ColorMap it
+// contains.
+type reverse struct {
+	ColorMap
+}
+
+// At implements the ColorMap interface for a Reversed ColorMap.
+func (r reverse) At(v float64) (color.Color, error) {
+	return r.ColorMap.At(r.Max() - (v - r.Min()))
+}
+
+// Palette implements the ColorMap interface for a Reversed ColorMap.
+func (r reverse) Palette(colors int) Palette {
+	c := r.ColorMap.Palette(colors).Colors()
+	c2 := make([]color.Color, len(c))
+	for i, j := 0, len(c)-1; i < j; i, j = i+1, j-1 {
+		c2[i], c2[j] = c[j], c[i]
+	}
+	return palette(c2)
+}