public static void Replace(this PlotModel collection, string trackerKey, GraphData data) {
var series = collection.Series.OfType<LineSeries>().FirstOrDefault(x => x.TrackerKey == trackerKey);
if (series == null) return;
series.Points.Clear();
if (data != null) {
series.Points.AddRange(data.Points.Select(x => new DataPoint(x.X, x.Y)));
}
}
}