need to flesh out this test more.

value.go

@@ -0,0 +1,46 @@
+package chart
+
+// Value is a chart value.
+type Value struct {
+	Style Style
+	Label string
+	Value float64
+}
+
+// Values is an array of Value.
+type Values []Value
+
+// Values returns the values.
+func (vs Values) Values() []float64 {
+	values := make([]float64, len(vs))
+	for index, v := range vs {
+		values[index] = v.Value
+	}
+	return values
+}
+
+// ValuesNormalized returns normalized values.
+func (vs Values) ValuesNormalized() []float64 {
+	return Normalize(vs.Values()...)
+}
+
+// Normalize returns the values normalized.
+func (vs Values) Normalize() []Value {
+	output := make([]Value, len(vs))
+	total := Sum(vs.Values()...)
+	for index, v := range vs {
+		output[index] = Value{
+			Style: v.Style,
+			Label: v.Label,
+			Value: (v.Value / total),
+		}
+	}
+	return output
+}
+
+// Value2 is a two axis value.
+type Value2 struct {
+	Style          Style
+	Label          string
+	XValue, YValue float64
+}