如何從特定 X 值的所有系列中獲取 Y 值（OxyPlot）

Question

我正在使用 OxyPlot。 我有一個帶有 PlotModel 的 PlotView。 有 2 個軸：yAxis 是 LinearAxis，xAxis 是 DateTimeAxis。 我有多個 LineSeries。 這是一個示例程序：

public MainWindow()
        {
            InitializeComponent();

            PlotModel plotModel = new PlotModel();
            plotView.Model = plotModel;

            plotModel.Axes.Clear();
            var yAxis = new LinearAxis();
            var xAxis = new DateTimeAxis();
            yAxis.IsZoomEnabled = false;
            yAxis.AbsoluteMinimum = -50;
            yAxis.AbsoluteMaximum = 450;
            yAxis.MajorGridlineStyle = LineStyle.Solid;
            xAxis.MajorGridlineStyle = LineStyle.Solid;
            xAxis.AbsoluteMinimum = DateTimeAxis.ToDouble(DateTime.Today);
            xAxis.AbsoluteMaximum = DateTimeAxis.ToDouble(DateTime.Today.AddDays(1));
            yAxis.IsPanEnabled = false;
            yAxis.IsZoomEnabled = false;
            plotModel.Axes.Add(yAxis);
            plotModel.Axes.Add(xAxis);

            var series1 = new LineSeries();
            series1.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today), 0));
            series1.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(4)), 100));
            series1.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(8)), 150));
            series1.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(12)), 50));
            series1.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(16)), 200));
            series1.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(20)), 150));
            series1.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(24)), 300));
            plotModel.Series.Add(series1);

            var series2 = new LineSeries();
            series2.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today), 0));
            series2.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(4)), 200));
            series2.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(8)), 200));
            series2.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(12)), 150));
            series2.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(16)), 300));
            series2.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(20)), 50));
            series2.Points.Add(new DataPoint(DateTimeAxis.ToDouble(DateTime.Today.AddHours(24)), 100));
            plotModel.Series.Add(series2);
        }

當我按住左鍵單擊時，我只能從我當前懸停的 LineSeries 中看到 Y 值。 我想獲取與鼠標指針當前所在的 X 值相對應的所有 Y 值。 我不需要自定義跟蹤器，我想在 plot 旁邊的 label 中顯示值。 還值得注意的是，這只是一個示例程序； 在我的主程序中，LineSeries 每個包含大約 50k 個點，這就是為什么我不能遍歷所有點來找到我想要的值。 這樣做最有效的方法是什么？

Answer 1

您可以對每個系列使用GetNearestPoint來獲取給定 X 的 Y 值。例如，

        PlotModel.TrackerChanged += (sender, eventArgs) =>
        {
            if (eventArgs.HitResult != null)
            {
                var currentPoint = eventArgs.HitResult.Position;
                var allYValuesForX = PlotModel.Series.Select(x => x.GetNearestPoint(currentPoint, true).DataPoint.Y);
                CurrentTrackerValue = $"X = {currentPoint.X}, Y ={string.Join(",", allYValuesForX)}";
            }

            UpdateLabel(CurrentTrackerValue);
        };