updates + tests

sma_series.go

@@ -11,6 +11,13 @@ const (
 	DefaultSimpleMovingAveragePeriod = 16
 )
 
+// Interface Assertions.
+var (
+	_ Series              = (*SMASeries)(nil)
+	_ FirstValuesProvider = (*SMASeries)(nil)
+	_ LastValuesProvider  = (*SMASeries)(nil)
+)
+
 // SMASeries is a computed series.
 type SMASeries struct {
 	Name  string
@@ -63,6 +70,17 @@ func (sma SMASeries) GetValues(index int) (x, y float64) {
 	return
 }
 
+// GetFirstValues computes the first moving average value.
+func (sma SMASeries) GetFirstValues() (x, y float64) {
+	if sma.InnerSeries == nil || sma.InnerSeries.Len() == 0 {
+		return
+	}
+	px, _ := sma.InnerSeries.GetValues(0)
+	x = px
+	y = sma.getAverage(0)
+	return
+}
+
 // GetLastValues computes the last moving average value but walking back window size samples,
 // and recomputing the last moving average chunk.
 func (sma SMASeries) GetLastValues() (x, y float64) {