LiveCharts 基于点值的折线图样式

Question

我使用LiveCharts和WPF绘制了一堆折线图，其中的内容和折线图的数量是在运行时确定的。所以我事先不知道会有多少LineSeries，它们的值是多少。但是，我知道每个 LineSeries 的 good 范围。例如，一个系列，我们称之为S1，其good 范围为 2+/-1。所以1到3之间的任何东西都被认为是好的。类似地，可能还有另一个，比如S2，范围是 30+/-2，所以 28 到 32 之间的任何值都是好的。

我想绘制折线图，​​以便将范围内的部分绘制为实线，但如果部分超出范围，它将是虚线/虚线。由于我有多个LineSeries，因此我将每个都绘制在自己的 Y 轴上。我的XAML 和代码如下所示：

<Grid>
    <lvc:CartesianChart Name="MyChart" Margin="4"
                        Series="{Binding SeriesCollection}"/>
</Grid>

后面的代码：

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public SeriesCollection SeriesCollection { get; set; }

    public MainWindow()
    {
        InitializeComponent();
        PlotGraph();
    }

    private void PlotGraph()
    {
        SeriesCollection = new SeriesCollection();
        var lineSeries1 = new LineSeries
        {
            Title = "S1",
            Values = new ChartValues<double>() { 2.3, 2.0, 3.1, 1.3, 0.5, 3.8, 7.3, 2.4, 1.2, 0.1 },
            DataLabels = true,
            Stroke = Brushes.Green,
            Fill = Brushes.Transparent,
            ScalesYAt = 0
        };

        var lineSeries2 = new LineSeries
        {
            Title = "S2",
            Values = new ChartValues<double>() { 32.5, 34.5, 29.5, 26.0, 25.8, 30.5, 32.1, 36.5, 32.4, 24.5 },
            DataLabels = true,
            Stroke = Brushes.HotPink,
            Fill = Brushes.Transparent,
            ScalesYAt = 1
        };

        SeriesCollection.Add(lineSeries1);
        SeriesCollection.Add(lineSeries2);

        MyChart.AxisY.Add(new Axis());
        MyChart.AxisY.Add(new Axis());

        DataContext = this;
    }
}

I found an example here PointState 是根据值着色的，但它对我不起作用，因为我在一个中绘制了多个系列。另外，我的图表有数千个点，所以我禁用了PointGeometry，因为如果我启用它们，它们无论如何都很难看到。

我想要的有可能吗？

Answer 1

我找到了一个解决方案，实际上是 2：您可以针对您的问题自定义实时图表，或者您像我在下面那样重新计算不同点：

它只是一种方式，一种回答你问题的想法，一切皆有可能，但需要一些代码....

绘图方法

    private void PlotGraph()
    {
        var points = new List<Point>() { new Point(0, 2.3), new Point(1, 2.0),
                                         new Point(2, 3.1), new Point(3, 1.3),
                                         new Point(4, 0.5), new Point(5, 3.8),
                                         new Point(6, 7.3), new Point(7, 2.4),
                                         new Point(8, 1.2), new Point(9, 0.1)};

        var range1 = new double[] { 1d, 3d };

        var otherpoints = CurvesMath.GetInterpolatedCubicSplinedCurve(points);
        var pointscurve = otherpoints.Select(p => p.Y).ToArray();

        SeriesCollection = new SeriesCollection();
        var lineSeries1 = new LineSeries
        {
            Title = "S1",
            Values = new ChartValues<double>(pointscurve),
            DataLabels = false,
            Stroke = Brushes.Transparent,
            Fill = Brushes.Transparent,
            ScalesYAt = 0,
            PointGeometrySize = 2,
            Configuration = Mappers.Xy<double>()
                                   .X((value, index) => index)
                                   .Y((value, index) => value)
                                   .Stroke((value, index) => value <= range1[0] || value >= range1[1] ? Brushes.Red : Brushes.Blue)
                                   .Fill((value, index) => value <= range1[0] || value >= range1[1] ? Brushes.Red : Brushes.Blue)
    };

        points = new List<Point>() { new Point(0, 32.5), new Point(1, 34.5),
                                     new Point(2, 29.5), new Point(3, 26.0),
                                     new Point(4, 25.8), new Point(5, 30.5),
                                     new Point(6, 32.1), new Point(7, 36.5),
                                     new Point(8, 32.4), new Point(9, 24.5)};
        var range2 = new double[] { 28d, 32d };
        otherpoints = CurvesMath.GetInterpolatedCubicSplinedCurve(points);
        pointscurve = otherpoints.Select(p => p.Y).ToArray();
        var lineSeries2 = new LineSeries
        {
            Title = "S2",
            Values = new ChartValues<double>(pointscurve),
            DataLabels = false,
            Stroke = Brushes.Transparent,
            Fill = Brushes.Transparent,
            ScalesYAt = 1,
            PointGeometrySize = 2,
            Configuration = Mappers.Xy<double>()
                                   .X((value, index) => index)
                                   .Y((value, index) => value)
                                   .Stroke((value, index) => value <= range2[0] || value >= range2[1] ? Brushes.Red : Brushes.Green)
                                   .Fill((value, index) => value <= range2[0] || value >= range2[1] ? Brushes.Red : Brushes.Green)
        };

        SeriesCollection.Add(lineSeries1);
        SeriesCollection.Add(lineSeries2);

        MyChart.AxisY.Add(new Axis());
        MyChart.AxisY.Add(new Axis());
        DataContext = this;
    }

---

xaml 文件：

<Grid>
    <lvc:CartesianChart Name="MyChart" Margin="4"
                    Series="{Binding SeriesCollection}"  >
    </lvc:CartesianChart>
</Grid>

---

插值三次样条（或贝塞尔曲线）

using System.Collections.Generic;
using System.Linq;
using System.Windows;

namespace WpfApp2
{
    public static class CurvesMath
    {
        private const int precision = 80;

        public static List<Point> GetInterpolatedCubicSplinedCurve(IList<Point> points)
        {
            var output = new List<Point>();
            int np = points.Count; // number of points
            double[] yCoords = new double[np]; // Newton form coefficients
            double[] xCoords = new double[np]; // x-coordinates of nodes
            double y;
            double x;

            if (np > 0)
            {
                for (int i = 0; i < np; i++)
                {
                    var p = points[i];
                    xCoords[i] = p.X;
                    yCoords[i] = p.Y;
                }
                if (np > 1)
                {
                    double[] a = new double[np];
                    double x1;
                    double x2;
                    double[] h = new double[np];
                    for (int i = 1; i <= np - 1; i++)
                    {
                        h[i] = xCoords[i] - xCoords[i - 1];
                    }
                    if (np > 2)
                    {
                        double[] sub = new double[np - 1];
                        double[] diag = new double[np - 1];
                        double[] sup = new double[np - 1];

                        for (int i = 1; i <= np - 2; i++)
                        {
                            diag[i] = (h[i] + h[i + 1]) / 3;
                            sup[i] = h[i + 1] / 6;
                            sub[i] = h[i] / 6;
                            a[i] = (yCoords[i + 1] - yCoords[i]) / h[i + 1] - (yCoords[i] - yCoords[i - 1]) / h[i];
                        }
                        SolveTridiag(sub, diag, sup, ref a, np - 2);
                    }

                    output.Add(points.First());

                    for (int i = 1; i <= np - 1; i++)
                    {
                        // loop over intervals between nodes
                        for (int j = 1; j <= precision; j++)
                        {
                            x1 = (h[i] * j) / precision;
                            x2 = h[i] - x1;
                            y = ((-a[i - 1] / 6 * (x2 + h[i]) * x1 + yCoords[i - 1]) * x2 +
                                 (-a[i] / 6 * (x1 + h[i]) * x2 + yCoords[i]) * x1) / h[i];
                            x = xCoords[i - 1] + x1;

                            output.Add(new Point(x, y));
                        }
                    }
                }
            }
            return output;
        }

        public static double SolveCubicSpline(IList<Point> knownSamples, double z)
        {
            int np = knownSamples.Count;

            if (np > 1)
            {
                if (knownSamples[0].X == z) return knownSamples[0].Y;

                double[] a = new double[np];
                double x1;
                double x2;
                double y;
                double[] h = new double[np];

                for (int i = 1; i <= np - 1; i++)
                {
                    h[i] = knownSamples[i].X - knownSamples[i - 1].X;
                }

                if (np > 2)
                {
                    double[] sub = new double[np - 1];
                    double[] diag = new double[np - 1];
                    double[] sup = new double[np - 1];

                    for (int i = 1; i <= np - 2; i++)
                    {
                        diag[i] = (h[i] + h[i + 1]) / 3;
                        sup[i] = h[i + 1] / 6;
                        sub[i] = h[i] / 6;

                        a[i] = (knownSamples[i + 1].Y - knownSamples[i].Y) / h[i + 1] -
                               (knownSamples[i].Y - knownSamples[i - 1].Y) / h[i];
                    }

                    // SolveTridiag is a support function, see Marco Roello's original code

                    // for more information at

                    // http://www.codeproject.com/useritems/SplineInterpolation.asp

                    SolveTridiag(sub, diag, sup, ref a, np - 2);
                }



                int gap = 0;

                double previous = double.MinValue;

                // At the end of this iteration, "gap" will contain the index of the interval

                // between two known values, which contains the unknown z, and "previous" will

                // contain the biggest z value among the known samples, left of the unknown z

                for (int i = 0; i < knownSamples.Count; i++)
                {
                    if (knownSamples[i].X < z && knownSamples[i].X > previous)
                    {
                        previous = knownSamples[i].X;
                        gap = i + 1;
                    }
                }

                x1 = z - previous;
                if (gap > h.Length - 1)
                    return z;

                x2 = h[gap] - x1;

                if (gap == 0)
                    return 0.0;

                y = ((-a[gap - 1] / 6 * (x2 + h[gap]) * x1 + knownSamples[gap - 1].Y) * x2 +
                     (-a[gap] / 6 * (x1 + h[gap]) * x2 + knownSamples[gap].Y) * x1) / h[gap];

                return y;
            }
            return 0;
        }

        private static void SolveTridiag(double[] sub, double[] diag, double[] sup, ref double[] b, int n)
        {
            /*                  solve linear system with tridiagonal n by n matrix a
                                using Gaussian elimination *without* pivoting
                                where   a(i,i-1) = sub[i]  for 2<=i<=n
                                        a(i,i)   = diag[i] for 1<=i<=n
                                        a(i,i+1) = sup[i]  for 1<=i<=n-1
                                (the values sub[1], sup[n] are ignored)
                                right hand side vector b[1:n] is overwritten with solution 
                                NOTE: 1...n is used in all arrays, 0 is unused */
            int i;
            /*                  factorization and forward substitution */
            for (i = 2; i <= n; i++)
            {
                sub[i] = sub[i] / diag[i - 1];
                diag[i] = diag[i] - sub[i] * sup[i - 1];
                b[i] = b[i] - sub[i] * b[i - 1];
            }
            b[n] = b[n] / diag[n];
            for (i = n - 1; i >= 1; i--)
            {
                b[i] = (b[i] - sup[i] * b[i + 1]) / diag[i];
            }
        }
    }
}

在结果中，您会看到所有坏的部分都是红色的