DefaultNull Value property in TeeChart

[vivekvr]

Hello,

I am trying to plot some field data using Teechart. Since the dield data I get is intermittent, the measuring device fills time instances where it doesn't have a measurement with 0. I want to plot only the valid measured values (i.e. leave out the zeros). Currently I go through the following loop to add the points one by one to a fastline series and use the fastline.TreatNull property to not paint these null points

For i = 0 To (numRecords - 1)
m_frmChart.chart.Series(0).Add(time(i), RSSI(i))
If RSSI(i) = 0 Then
m_frmChart.chart.Series(0.SetNull(i)
End If
Next

Can I (and if Yes how) use the DefaultNull property of the series so that all I would have to do is
m_frmchart.chart.series(0).defaultnullvalue=0
m_frmchart.chart.series(0).add(RSSI)
m_frmchart.chart.fastlint1.TreatNulls=DoNotPaint

(Series(0) in this instance is fastline1).

Thanks,
Vivek

[Narcís]

Hi Vivek,

You have 2 options:

1. Using SetNull:

Code: Select all

		public Form1()
		{
			InitializeComponent();
			InitializeChart();
		}

		private void InitializeChart()
		{
			Steema.TeeChart.Styles.Line line1 = new Steema.TeeChart.Styles.Line(tChart1.Chart);
			line1.DefaultNullValue = 0;
			line1.TreatNulls = Steema.TeeChart.Styles.TreatNullsStyle.DoNotPaint;

			Random y = new Random();

			for (int i = 0; i < 100; i++)
			{
				if (i % 5 == 0) 
				{
					line1.Add(line1.DefaultNullValue);
					line1.SetNull(i);
				}
				else
				{
					line1.Add(y.Next());
				}
			}
		}

2. Adding a point being transparent:

Code: Select all

		private void InitializeChart()
		{
			Steema.TeeChart.Styles.Line line1 = new Steema.TeeChart.Styles.Line(tChart1.Chart);
			line1.DefaultNullValue = 0;
			line1.TreatNulls = Steema.TeeChart.Styles.TreatNullsStyle.DoNotPaint;

			Random y = new Random();

			for (int i = 0; i < 100; i++)
			{
				if (i % 5 == 0) 
				{
					line1.Add(line1.DefaultNullValue, Color.Transparent);
					//line1.SetNull(i);
				}
				else
				{
					line1.Add(y.Next());
				}
			}
		}

3. Calling Add() method without any argument:

Code: Select all

		private void InitializeChart()
		{
			Steema.TeeChart.Styles.Line line1 = new Steema.TeeChart.Styles.Line(tChart1.Chart);
			line1.DefaultNullValue = 0;
			line1.TreatNulls = Steema.TeeChart.Styles.TreatNullsStyle.DoNotPaint;

			Random y = new Random();

			for (int i = 0; i < 100; i++)
			{
				if (i % 5 == 0) 
				{
					line1.Add();
					//line1.SetNull(i);
				}
				else
				{
					line1.Add(y.Next());
				}
			}
		}

[vivekvr]

Hi,

Thanks for the clarification. My understanding of the defaultnullvalue was a little different. The name seems to suggest that one you specify the defaultnullvalue, any point in the series whose value was equal to the defaultnullvalue would be treated as a null point.

The only problem I see with the approaches you had suggested is that I need to loop through the data series and add one point at a time. I would think that this would be slower than specifying a value to be interpreted as a null and just adding the entire series i.e.
Series(0).defaultNullValue=0
Series(0).Add(data) where data() is the data I want to plot.

Do you have anyway by which I can add data to a series in a single shot and specify points with a particular value to be treated as a null?

Thanks,
Vivek

[Narcís]

Hi Vivek,

In that case you should have a colour field in your datatable having Color.Transparent for those points you want to be null so that you can do something like this:

Code: Select all

		public Form1()
		{
			InitializeComponent();
			InitializeChart();
		}

		private void InitializeChart()
		{
			Steema.TeeChart.Styles.FastLine fastLine1 = new Steema.TeeChart.Styles.FastLine(tChart1.Chart);
			fastLine1.DefaultNullValue = 0;
			fastLine1.TreatNulls = Steema.TeeChart.Styles.TreatNullsStyle.DoNotPaint;

			fastLine1.DataSource = GetData();
			fastLine1.YValues.DataMember = "Y";
			fastLine1.ColorMember = "Color";
		}

		private DataTable GetData()
		{
			DataTable TeeDataTable = new DataTable();

			DataRow newRow;
			
			DataColumn yval = new DataColumn("Y", typeof(double));
			DataColumn color = new DataColumn("Color", typeof(Color));
						
			TeeDataTable.Columns.Add(yval);
			TeeDataTable.Columns.Add(color);

			for (int i = 0; i < 100; i++)
			{
				newRow = TeeDataTable.NewRow();
				if (i % 5 == 0)
				{
					newRow[yval] = 0;
					newRow[color] = Color.Transparent;
				}
				else
				{
					newRow[yval] = i;
					newRow[color] = Color.Empty;
				}
				
				TeeDataTable.Rows.Add(newRow);
			}

			return TeeDataTable;
		} 

[Narcís]

Hi Vivek,

I forgot to tell you that I have also added your request to the wish-list to be considered for inclusion in future releases.