Empty Points

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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.

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
NOTE

20.1 Demo Center: Launch the Empty Points demo

To make a point empty, do one of the following:

  • 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.

    using DevExpress.XtraCharts;
    using System;
    using System.Collections.Generic;
    using System.Windows.Forms;
    namespace EmptyPointRepsentation {
        public partial class Form1 : Form {
            ChartControl chart { get { return chartControl1; } }
            public Form1() {
                InitializeComponent();
                Series series = new Series();
                // The following line adds an empty series point to a series.
                series.Points.Add(new SeriesPoint(new DateTime(2019,1,1)));
                chart.Series.Add(series);
            }
        }
    }
    
  • or set a data point's value to Double.NaN in a data source.

    using DevExpress.XtraCharts;
    using System;
    using System.Collections.Generic;
    using System.Windows.Forms;
    
    namespace EmptyPointRepsentation {
        public partial class Form1 : Form {
            ChartControl chart { get { return chartControl1; } }
            public Form1() {
                InitializeComponent();
            }
            private void OnFormLoad(object sender, EventArgs e) {
                chart.DataSource = DataPoint.GetPoints();
                Series series1 = new Series("Politics", ViewType.Line);
                series1.SetDataMembers("Date", "Politics");
                Series series2 = new Series("Entertainment", ViewType.Line);
                series2.SetDataMembers("Date", "Entertainment");
                Series series3 = new Series("Travel", ViewType.Line);
                series3.SetDataMembers("Date", "Travel");
                chart.Series.AddRange(new Series[] { series1, series2, series3 });
            }
        }
        public class DataPoint {
            public DateTime Date { get; set; }
            public Double Politics { get; set; }
            public Double Entertainment { get; set; }
            public Double Travel { get; set; }
            public static List<DataPoint> GetPoints() {
                return new List<DataPoint> {
                        new DataPoint { Date = new DateTime(2016,11,1), Politics = 65,   Entertainment = 56, Travel = 45 },
                        new DataPoint { Date = new DateTime(2016,11,2), Politics = 78,   Entertainment = 45, Travel = 40 },
                        new DataPoint { Date = new DateTime(2016,11,3), Politics = 95,   Entertainment = 70, Travel = 56 },
                        new DataPoint { Date = new DateTime(2016,11,4), Politics = 110,  Entertainment = 82, Travel = 47 },
                        new DataPoint { Date = new DateTime(2016,11,5), Politics = 108,  Entertainment = 80, Travel = 38 },
                        new DataPoint { Date = new DateTime(2016,11,6), Politics = 52,   Entertainment = 20, Travel = 31 },
                        new DataPoint { Date = new DateTime(2016,11,7), Politics = 46,   Entertainment = 10, Travel = 27 },
                        new DataPoint { Date = new DateTime(2016,11,8), Politics = 70,   Entertainment = Double.NaN, Travel = 27 },
                        new DataPoint { Date = new DateTime(2016,11,9), Politics = 86,   Entertainment = Double.NaN, Travel = 42 },
                        new DataPoint { Date = new DateTime(2016,11,10), Politics = 92,  Entertainment = 65, Travel = Double.NaN},
                        new DataPoint { Date = new DateTime(2016,11,11), Politics = 105, Entertainment = 45, Travel = 37 },
                        new DataPoint { Date = new DateTime(2016,11,12), Politics = 115, Entertainment = 56, Travel = 21 },
                        new DataPoint { Date = new DateTime(2016,11,13), Politics = 75,  Entertainment = 10, Travel = 10 },
                        new DataPoint { Date = new DateTime(2016,11,14), Politics = 65,  Entertainment = 0 , Travel = 5  }
                    };
            }
        }
    }
    

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

Missing points are represented as empty points if the ScaleOptionsBase.ProcessMissingPoints property is set to InsertEmptyPoints.

TIP

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