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c# - 如何从特定 X 值的所有系列中获取 Y 值（OxyPlot）

问题描述

我正在使用 OxyPlot。我有一个带有 PlotModel 的 PlotView。有 2 个轴：yAxis 是 LinearAxis，xAxis 是 DateTimeAxis。我有多个 LineSeries。这是一个示例程序：

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);
        }

当我按住左键单击时，我只能从我当前悬停的 LineSeries 中看到 Y 值。我想获取与鼠标指针当前所在的 X 值相对应的所有 Y 值。我不需要自定义跟踪器，我想在绘图旁边的标签中显示值。还值得注意的是，这只是一个示例程序；在我的主程序中，LineSeries 每个包含大约 50k 个点，这就是为什么我不能遍历所有点来找到我想要的值。这样做最有效的方法是什么？

标签： c#chartsoxyplot

解决方案

您可以使用GetNearestPoint每个系列来获取给定 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);
        };

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