Allow to limit the number of entries in time series plots (#53)

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [[v0.9.0]](https://github.com/mlange-42/arche-pixel/compare/v0.8.1...v0.9.0)
+
+### Features
+
+* Allows to limit the number of entries in time series plots (#53)
+
 ## [[v0.8.1]](https://github.com/mlange-42/arche-pixel/compare/v0.8.0...v0.8.1)
 
 ### Features

plot/time_series.go

@@ -24,6 +24,7 @@ type TimeSeries struct {
 	Columns        []string     // Columns to show, by name. Optional, default all.
 	UpdateInterval int          // Interval for getting data from the the observer, in model ticks. Optional.
 	Labels         Labels       // Labels for plot and axes. Optional.
+	MaxRows        int          // Maximum number of rows to keep. Zero means unlimited. Optional.
 
 	indices []int
 	headers []string
@@ -36,6 +37,9 @@ type TimeSeries struct {
 func (t *TimeSeries) append(x float64, values []float64) {
 	for i := 0; i < len(t.series); i++ {
 		t.series[i] = append(t.series[i], plotter.XY{X: x, Y: values[i]})
+		if t.MaxRows > 0 && len(t.series[i]) > t.MaxRows {
+			t.series[i] = t.series[i][len(t.series[i])-t.MaxRows:]
+		}
 	}
 }
 

plot/time_series_test.go

@@ -50,6 +50,7 @@ func TestTimeSeries_Columns(t *testing.T) {
 		With(&plot.TimeSeries{
 			Observer: &RowObserver{},
 			Columns:  []string{"A", "C"},
+			MaxRows:  50,
 		}))
 
 	m.AddSystem(&system.FixedTermination{