Empty Points

Jan 22, 2025
10 minutes to read

Empty points are points with undefined Values. This document describes how the Chart Control processes empty points.

The Chart displays empty points as breaks in the Line or Area series views, and missing points or bars in other series view types.

Line View

The following table contains data for the charts above:

Date	Politics	Entertainment	Travel
01-Nov-16	65	56	45
02-Nov-16	78	45	40
03-Nov-16	95	70	56
04-Nov-16	110	82	47
05-Nov-16	108	80	38
06-Nov-16	52	20	31
07-Nov-16	46	10	27
08-Nov-16	70		27
09-Nov-16	86		42
10-Nov-16	92	65
11-Nov-16	108	45	37
12-Nov-16	115	56	21
13-Nov-16	75	10	10
14-Nov-16	65	0	5

To create an empty point, execute one of the following actions:

Leave a point’s value blank if you use the Chart Designer to add points to a series.
Use the SeriesPoint‘s class constructors that take only an argument as a parameter if you add points to a series in code.
Set a data point’s value to Double.NaN in a data source.

You can use the SeriesPoint.IsEmpty property to check whether a point is empty.

Tip

You can use scale breaks to hide specific data ranges from an axis.
To limit data displayed in a chart, configure visual and whole axis ranges.
If you use an argument axis with a date-time scale, you can exclude holidays, weekends, or specified hours from a scale. Refer to the following help topic for more information: Work Time and Workday Configuration.

Define How to Handle Empty Points

Use a series view’s EmptyPointOptions property to access empty point settings. Specify the EmptyPointOptions.ProcessPoints property to select the manner in which the chart control should handle empty points.

For example, use the following code to display points with predicted values instead of empty points.

C#
VB.NET

csharp

using DevExpress.XtraCharts;

    public Form1() {
        InitializeComponent();        
        //...
        BarSeriesView view = (BarSeriesView)series.View;
        EmptyPointOptions emptyPointOptions = view.EmptyPointOptions;
        emptyPointOptions.ProcessPoints = ProcessEmptyPointsMode.Interpolate;
    }

Imports DevExpress.XtraCharts

    Public Sub New()
        InitializeComponent()
        '...
        Dim view As BarSeriesView = CType(series.View, BarSeriesView)
        Dim emptyPointOptions As EmptyPointOptions = view.EmptyPointOptions
        emptyPointOptions.ProcessPoints = ProcessEmptyPointsMode.Interpolate
    End Sub

Customize Appearance of Empty Points

Appearance settings of empty points depends on the series view type. Depending on the view, cast the EmptyPointOptions property value to one of the following classes and configure empty point appearance settings:

EmptyPointOptions – Contains common empty point settings and can be used for all series views.
LineEmptyPointOptions – Contains settings specific to line series views (for example, LineStyle).
AreaEmptyPointOptions – Contains settings specific to area series views (for example, FillStyle).

The example below configures empty point appearance for line, area, and bar series views. Empty points are painted gray:

C#
VB.NET

csharp

LineSeriesView view1 = (LineSeriesView)series1.View;
view1.MarkerVisibility = DevExpress.Utils.DefaultBoolean.True;
LineEmptyPointOptions lineEmptyPointOptions = view1.EmptyPointOptions;
lineEmptyPointOptions.ProcessPoints = ProcessEmptyPointsMode.Interpolate;
lineEmptyPointOptions.Color = Color.DarkGray;
lineEmptyPointOptions.LineStyle.DashStyle = DashStyle.Dash;
lineEmptyPointOptions.LineStyle.Thickness = 2;

AreaSeriesView view2 = (AreaSeriesView)series2.View;
AreaEmptyPointOptions areaEmptyPointOptions = view2.EmptyPointOptions;
areaEmptyPointOptions.ProcessPoints = ProcessEmptyPointsMode.Interpolate;
areaEmptyPointOptions.FillStyle.FillMode = FillMode.Solid;
areaEmptyPointOptions.Color = Color.DarkGray;
areaEmptyPointOptions.Border.Color = Color.Gray;
areaEmptyPointOptions.Border.Thickness = 2;

SideBySideBarSeriesView view3 = (SideBySideBarSeriesView)series3.View;
EmptyPointOptions emptyPointOptions = view3.EmptyPointOptions;
emptyPointOptions.ProcessPoints = ProcessEmptyPointsMode.Interpolate;
emptyPointOptions.Color = Color.FromArgb(100, Color.DarkGray);

Dim view1 As LineSeriesView = CType(series1.View, LineSeriesView)
view1.MarkerVisibility = DevExpress.Utils.DefaultBoolean.True
Dim lineEmptyPointOptions As LineEmptyPointOptions = view1.EmptyPointOptions
lineEmptyPointOptions.ProcessPoints = ProcessEmptyPointsMode.Interpolate
lineEmptyPointOptions.Color = Color.DarkGray
lineEmptyPointOptions.LineStyle.DashStyle = DashStyle.Dash
lineEmptyPointOptions.LineStyle.Thickness = 2

Dim view2 As AreaSeriesView = CType(series2.View, AreaSeriesView)
Dim areaEmptyPointOptions As AreaEmptyPointOptions = view2.EmptyPointOptions
areaEmptyPointOptions.ProcessPoints = ProcessEmptyPointsMode.Interpolate
areaEmptyPointOptions.FillStyle.FillMode = FillMode.Solid
areaEmptyPointOptions.Color = Color.DarkGray
areaEmptyPointOptions.Border.Color = Color.Gray
areaEmptyPointOptions.Border.Thickness = 2

Dim view3 As SideBySideBarSeriesView = CType(series3.View, SideBySideBarSeriesView)
Dim emptyPointOptions As EmptyPointOptions = view3.EmptyPointOptions
emptyPointOptions.ProcessPoints = ProcessEmptyPointsMode.Interpolate
emptyPointOptions.Color = Color.FromArgb(100, Color.DarkGray)

Show Isolated Points

The Chart does not draw a point between two empty points. To display a point in this case, enable the ShowIsolatedPoints property.

ShowIsolatedPoints = true	ShowIsolatedPoints = false

C#
VB.NET

csharp

LineSeriesView view = chart.Series[0].View as LineSeriesView;
view.ShowIsolatedPoints = true;

Dim view As LineSeriesView = TryCast(chart.Series(0).View, LineSeriesView)
view.ShowIsolatedPoints = True

Empty Points Specifics

The Chart Control does not display series labels, tooltips, and the crosshair cursor label for empty points.
If a data source contains missing records in arguments, data points are not created. Set the ScaleOptionsBase.ProcessMissingPoints property to InsertEmptyPoints to handle missing points as empty points.
Empty points are ignored when you aggregate or resample Chart’s data and the chart contains data next to empty points within the specified interval of the measurement unit.