WebChart .Net Question

[Joy]

Hi,

We are trying to figure out a way to set up a WebChart in .NET to only display a Line when there is data and not draw a line to zero when there is no data.

Here is what we have now:

http://bwing.engr.colostate.edu/Arkansa ... erage%20EC

As you can see, wherever the data stops, it draws a line to zero. Is there anyway it can just stop right where it is and pick up again later when there is data?

Thanks!

Joy

[Narcís]

Hi Joy,

Yes, you can use TreatNulls property for that as shown in the All Features\Welcome !\New in Series\Line/Horizontal line TreatNulls example at the features demo, available at TeeChart's program group.

[Joy]

Hi,

Which version of TeeChart is that in? Because I can't find it in my version - it's TeeChart vs.2

[Narcís]

Hi Joy,

That's version 3. In v2 you can use IgnoreNulls property as shown in the example at All Features\Welcome !\Chart styles\Standard\Fast Line\Nulls and stairs in the features demo, available at TeeChart's program group.

[Joy]

Thank you very much but after going over that example I'm still unable to get it to work and I'm not sure what I'm doing wrong. If you have a moment, could you glance over this code and let me know if I'm doing something wrong?

Basically I'm looping through a dataset from a database and I'm adding the values to the fastLine as I go and then I'm looping through the dataset again a second time to set the Null values. For some reason, unless I do this in two steps the graph data shows up incorrectly. And then I set the IgnoreNulls property to true but it does the exact same thing as before - it draws a line to zero. Any help would be greatly appreciated!

Thank you!

Dim Chart1 As Steema.TeeChart.Chart = WebChart1.Chart
Chart1.Legend.CheckBoxes = True
Chart1.Aspect.View3D = False

Dim fastLine As Steema.TeeChart.Styles.FastLine = New Steema.TeeChart.Styles.FastLine(WebChart1.Chart)

For i = 0 To oDS2.Tables(0).Rows.Count - 1
For j = 1 To oDS2.Tables(0).Columns.Count - 1
If oDS2.Tables(0).Columns(j).DataType.Name <> "DateTime" Then
If IsNumeric(oDS2.Tables(0).Rows(i).Item(j)) = True Then
fastLine.Add(CType(oDS2.Tables(0).Rows(i).Item("Measurement_Date"), Date), CType(oDS2.Tables(0).Rows(i).Item(j), Double))
Else
fastLine.Add(CType(oDS2.Tables(0).Rows(i).Item("Measurement_Date"), Date), CType(0, Double))
End If
End If
Next
Next

For i = 0 To oDS2.Tables(0).Rows.Count - 1
For j = 1 To oDS2.Tables(0).Columns.Count - 1
If oDS2.Tables(0).Columns(j).DataType.Name <> "DateTime" Then
If IsDBNull(oDS2.Tables(0).Rows(i).Item(j)) Then
fastLine.SetNull(i, True)
End If
End If
Next
Next

fastLine.IgnoreNulls = True
fastLine.Stairs = True
fastLine.Title = strColumnName

fastLine.VertAxis = Steema.TeeChart.Styles.VerticalAxis.Left
fastLine.YValues.DataMember = strColumnName
fastLine.XValues.DataMember = "Measurement Date"
fastLine.XValues.DateTime = True

Chart1.Aspect.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality
Chart1.Aspect.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit
Chart1.Series.Add(fastLine)

Chart1.Header.Text = Title
Chart1.Axes.Left.Labels.Text = strColumnName
Chart1.Axes.Bottom.Labels.Text = "Dates"

[Joy]

Correction: in the previous post I incorrectly wrote one statement.

"fastLine.IgnoreNulls = True" should be "fastLine.IgnoreNulls = False" Although interestingly it does the same thing regardless of what this property is set to.

[Narcís]

Hi Joy,

Thanks for the information but I'm not able to see anything wrong with your code at first glance. Would you be so kind to arrange a simple example project we can run "as-is" to reproduce the problem here?

You can either post your files at news://www.steema.net/steema.public.attachments newsgroup or at our upload page.

Thanks in advance.

[Joy]

Hi,

I have prepared an ASP.NET application for you called TestGraph and uploaded it to your server demonstrating the problem we are having. When I run this example, I get the same results as my other application.

After playing with it a lot yesterday after writing you, I was able to get the graph to show some of the gaps - however, at the end of the data there are a lot of nulls in a row and for some reason the project shows it as a line even though earlier on in the series it works just fine. I stepped through my code to make sure I was really setting those points to null and not something else and as far as I can tell it's set up correctly in the code.

I've also downloaded all the updates for TeeChart vs.2 although I wasn't sure if the TeeChart.dlls were automatically updated or if I needed to go in and change that somewhere.

I guess that's about it - any help you can provide would be greatly appreciated. Thanks!

Joy

[Narcís]

Hi Joy,

Thanks for the example project.

The main problem is that when checking if a point should be null or not you are not adding it to the chart, therefore SetNull sets the wrong point to null and moreover, the series doesn't have all data points and existing points are set to null when they shouldn't. Below there's the code I used for getting your example to work.

Code: Select all

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'Put user code to initialize the page here
        Dim sr As StreamReader = New StreamReader(Request.MapPath("ArkansasValleyData.txt"))
        Dim Title, LegendTitle, strColumnName As String
        Dim m_tbl As DataTable = New DataTable("DebugTable")
        Dim m_row As DataRow
        Dim m_Array() As String
        Dim line As String
        Dim i As Integer

        Try
            line = sr.ReadLine()
            m_tbl.Columns.Add("Date").DataType = GetType(System.DateTime)
            m_tbl.Columns.Add("Value").DataType = GetType(System.Double)

            line = sr.ReadLine()
            While Not line = ""
                m_Array = Split(line, vbTab)
                m_row = m_tbl.NewRow()
                m_row(0) = m_Array(1)
                If m_Array.Length >= 3 Then
                    If m_Array(2) = Nothing Then
                        m_row(1) = System.DBNull.Value
                    Else
                        m_row(1) = m_Array(2)
                    End If
                Else
                    m_row(1) = System.DBNull.Value
                End If
                m_tbl.Rows.Add(m_row)
                line = sr.ReadLine()

                Dim Chart1 As Steema.TeeChart.Chart = WebChart1.Chart
                Chart1.Legend.Visible = False
                Chart1.Aspect.View3D = False

                Dim fastLine1 As Steema.TeeChart.Styles.FastLine = New Steema.TeeChart.Styles.FastLine(WebChart1.Chart)
                fastLine1.VertAxis = Steema.TeeChart.Styles.VerticalAxis.Left

                Title = "Well #303, Study Region, Arkansas River Valley"
                strColumnName = "Water Table Depth (m)"
                LegendTitle = "Water Table Depth"

                For i = 0 To m_tbl.Rows.Count - 1
                    If IsNumeric(m_tbl.Rows(i).Item(1)) Then
                        fastLine1.Add(CType(m_tbl.Rows(i).Item("Date"), Date), CType(m_tbl.Rows(i).Item(1), Double))
                    Else
                        fastLine1.Add(CType(m_tbl.Rows(i).Item("Date"), Date), 0)
                        fastLine1.SetNull(i)
                    End If
                Next

                fastLine1.Title = strColumnName
                'fastLine1.YValues.DataMember = strColumnName
                'fastLine1.XValues.DataMember = "Measurement Date"
                fastLine1.XValues.DateTime = True

                Chart1.Header.Text = Title
                'Chart1.Axes.Left.Labels.Text = strColumnName
                Chart1.Axes.Bottom.Labels.Text = "Dates"
                fastLine1.IgnoreNulls = False
                fastLine1.Stairs = True
                Chart1.Axes.Bottom.Automatic = True
                Chart1.Axes.Left.Automatic = True
                Chart1.Axes.Left.MinimumOffset = 50
                Chart1.Axes.Left.MaximumOffset = 50
            End While
        Catch oex As Exception
            Console.WriteLine(oex.ToString)
        Finally
            sr.Close()
        End Try
    End Sub

[Joy]

Thank you so much! That did the trick!