问题
I draw a bunch of line graphs using LiveCharts and WPF, where the contents and the number of line charts are determined at run time. So I don't know in advance how many LineSeries will be there, and what their values will be. However, I know the good range for each LineSeries. For example, one series, let's call it S1 has a good range of 2+/-1. So anything between 1 and 3 are considered to be good. Similarly there can be another, say S2 where range is 30+/-2, so anything between 28 and 32 is good.
I would like to draw the line graph so that sections that are within range are drawn as a solid line, but if a section is outside the range, it would be a dotted/dash line. Since I have multiple LineSeries in one, I have plotted each in its own Y-axis. My XAML and code looks like this:
<Grid>
<lvc:CartesianChart Name="MyChart" Margin="4"
Series="{Binding SeriesCollection}"/>
</Grid>
Code behind:
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 that the PointState is colored based on values, but it doesn't work for me because I draw multiple series in one. Also, my graph has thousands of points so I have disabled PointGeometry since if I enable them they will be very hard to see anyway.
Is what I want possible at all?
回答1:
i have found a solution, in fact 2: either you customize livechart to your problem or you recalculate the differents points like i do below:
its just a way, an idea to answer to your question, all things are possible, but need some line of codes....
the plotgraph method
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;
}
the xaml file:
<Grid>
<lvc:CartesianChart Name="MyChart" Margin="4"
Series="{Binding SeriesCollection}" >
</lvc:CartesianChart>
</Grid>
the interpolation cubic spline (or bezier)
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];
}
}
}
}
in the result you see all bad parts with the color RED
来源：https://stackoverflow.com/questions/58243687/livecharts-line-graph-style-based-on-point-value