updates + tests

ema_series.go

@@ -7,6 +7,13 @@ const (
 	DefaultEMAPeriod = 12
 )
 
+// Interface Assertions.
+var (
+	_ Series              = (*EMASeries)(nil)
+	_ FirstValuesProvider = (*EMASeries)(nil)
+	_ LastValuesProvider  = (*EMASeries)(nil)
+)
+
 // EMASeries is a computed series.
 type EMASeries struct {
 	Name  string
@@ -66,6 +73,19 @@ func (ema *EMASeries) GetValues(index int) (x, y float64) {
 	return
 }
 
+// GetFirstValues computes the first moving average value.
+func (ema *EMASeries) GetFirstValues() (x, y float64) {
+	if ema.InnerSeries == nil {
+		return
+	}
+	if len(ema.cache) == 0 {
+		ema.ensureCachedValues()
+	}
+	x, _ = ema.InnerSeries.GetValues(0)
+	y = ema.cache[0]
+	return
+}
+
 // GetLastValues computes the last moving average value but walking back window size samples,
 // and recomputing the last moving average chunk.
 func (ema *EMASeries) GetLastValues() (x, y float64) {