Table of Contents

Annotations

Arrow annotations with background

Plt.Create()
    .AddSubPlot(1, 1, 1, ax => ax
        .WithTitle("Annotation Enhancements")
        .Plot(x, y, line => { line.Label = "Data"; })
        .Annotate("Peak", 8, 8.9, ann =>
        {
            ann.ArrowTargetX = 8;
            ann.ArrowTargetY = 8.9;
            ann.ArrowStyle   = ArrowStyle.FancyArrow;
            ann.BackgroundColor = Colors.White;
        })
        .Annotate("Rotated label", 2, 4.5, ann =>
        {
            ann.Rotation  = -30;
            ann.Alignment = TextAlignment.Center;
        }))
    .Save("annotations.svg");

Annotations

Horizontal reference line

Mark thresholds, targets, or boundaries:

Plt.Create()
    .AddSubPlot(1, 1, 1, ax => ax
        .Plot(x, y, s => s.Label = "Data")
        .AxHLine(5.0, l =>
        {
            l.Color = Colors.Red;
            l.LineStyle = LineStyle.Dashed;
            l.LineWidth = 1.5;
            l.Label = "Threshold";
        })
        .WithLegend())
    .Save("hline.svg");

Vertical reference line

Plt.Create()
    .AddSubPlot(1, 1, 1, ax => ax
        .Plot(x, y)
        .AxVLine(5.0, l =>
        {
            l.Color = Colors.Green;
            l.LineStyle = LineStyle.DashDot;
            l.Label = "Event";
        })
        .WithLegend())
    .Save("vline.svg");

Shaded span regions

Highlight a range on the axis:

Plt.Create()
    .AddSubPlot(1, 1, 1, ax => ax
        .Plot(x, y, s => s.Label = "Signal")
        // Vertical span: highlight an X range
        .AxVSpan(3.0, 6.0, s =>
        {
            s.Color = Colors.Yellow;
            s.Alpha = 0.3;
            s.Label = "Active period";
        })
        // Horizontal span: highlight a Y range
        .AxHSpan(4.0, 7.0, s =>
        {
            s.Color = Colors.LightBlue;
            s.Alpha = 0.2;
            s.Label = "Target range";
        })
        .WithLegend())
    .Save("spans.svg");

Multiple reference lines

Plt.Create()
    .AddSubPlot(1, 1, 1, ax => ax
        .Plot(x, y, s => s.Label = "Price")
        .AxHLine(20, l => { l.Color = Colors.Green; l.LineStyle = LineStyle.Dashed; l.Label = "Support"; })
        .AxHLine(70, l => { l.Color = Colors.Red;   l.LineStyle = LineStyle.Dashed; l.Label = "Resistance"; })
        .AxVLine(5,  l => { l.Color = Colors.Gray;  l.LineStyle = LineStyle.Dotted; l.Label = "Earnings date"; })
        .WithLegend(LegendPosition.UpperLeft))
    .Save("multi_ref.svg");

Combining annotations with math text

Plt.Create()
    .AddSubPlot(1, 1, 1, ax => ax
        .Plot(x, y)
        .Annotate(@"$R^{2} = 0.97$", 3, 7, ann =>
        {
            ann.BackgroundColor = Colors.White;
            ann.FontSize = 14;
        })
        .Annotate(@"$\frac{\partial f}{\partial x} = 0$", 8, 3, ann =>
        {
            ann.ArrowTargetX = 8;
            ann.ArrowTargetY = y[8];
            ann.ArrowStyle = ArrowStyle.FancyArrow;
        }))
    .Save("math_annotations.svg");

Fluent API reference

Method Parameters Description
.Annotate(text, x, y, cfg?) text, position Text annotation at (x, y)
.Annotate(text, x, y, arrowX, arrowY, cfg?) + arrow target Text with arrow pointing to target
.AxHLine(y, cfg?) y position Horizontal reference line
.AxVLine(x, cfg?) x position Vertical reference line
.AxHSpan(yMin, yMax, cfg?) y range Horizontal shaded band
.AxVSpan(xMin, xMax, cfg?) x range Vertical shaded band

Annotation properties

Property Type Description
ArrowTargetX/Y double Arrow endpoint
ArrowStyle ArrowStyle FancyArrow, Simple, ...
BackgroundColor Color Text background
FontSize double Font size
Rotation double Text rotation in degrees
Alignment TextAlignment Left, Center, Right

ReferenceLine properties

Property Type Description
Color Color Line color
LineStyle LineStyle Solid, Dashed, Dotted, DashDot
LineWidth double Line width
Label string Legend label

SpanRegion properties

Property Type Description
Color Color Fill color
Alpha double Transparency (0–1)
Label string Legend label
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