Zedgraph about xaxis(hours)

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hello!

I have problem to show hours in graph.

I have this registers in DataBase MySQL:

VB

hora:                temperatura:
8:34:14             +025.52
8:35:15             +026.43
8:36:16             +026.24
8:37:17             +027.50
   .                    .
   .                    .
   .                    .
   .                    .

so I'm graphing it:
https://i.stack.imgur.com/RZxQz.jpg

the XAxis is showing the hours "70000, 80000, 90000,...."
I want the Xaxis show hours like "7:00:00 8:00:00 9:00:00"

so, I have the hours stored in database.

this is the code:

Private Sub CreateGraph(ByVal zgc As ZedGraphControl)
       Try
           Dim query As String = "SELECT * from termocuplas WHERE id_modulo = '#03H' AND fecha = '2019-08-27' ORDER BY fecha ASC, hora ASC"    'ORDER BY fecha ASC
           Dim connection As New MySqlConnection(connStr)
           Dim cmd As New MySqlCommand(query, connection)
           connection.Open()
           reader = cmd.ExecuteReader()

           Dim myPane As GraphPane = zgc.GraphPane
           myPane.Title.Text = "Termocupla"
           myPane.XAxis.Title.Text = "Tiempo(hh:mm:ss)"
           myPane.XAxis.Scale.MagAuto = False

           myPane.YAxis.Title.Text = "Temperatura °C"
           myPane.YAxis.Scale.MagAuto = False

           Dim list1 = New PointPairList()
           Dim y As Single
           Dim x As Single

           If reader.Read Then
               While reader.Read()
                   y = Convert.ToSingle(Replace(reader.GetString(3), ".", ","))
                   x = Convert.ToSingle(Replace(reader.GetString(11), ":", ""))
                   list1.Add(x, y)
               End While
               reader.Close()
           Else
               MessageBox.Show("Nothing")
           End If

           Dim myCurve As LineItem = myPane.AddCurve("Termocupla Vapor", list1, Color.Red, SymbolType.None)
           myCurve.Line.Fill = New Fill(Color.White, Color.Red, 45.0F) ' Make the symbols opaque by filling them with white
           myCurve.Symbol.Fill = New Fill(Color.White) ' Fill the axis background with a color gradient
           myPane.Chart.Fill = New Fill(Color.White, Color.LightGoldenrodYellow, 45.0F) ' Fill the pane background with a color gradient
           myPane.Fill = New Fill(Color.White, Color.FromArgb(220, 220, 255), 45.0F)
           zgc.AxisChange()
           connection.Close()
       Catch ex As Exception
           Console.WriteLine(ex.Message)
       End Try

   End Sub

What I have tried:

so, what can I do to show the hours correctly?

Posted 27-Aug-19 3:28am

Member 14560567

Updated 27-Aug-19 7:42am

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2 solutions

Solution 1

You probably need to store the "x value" as a "date time".

Then when you specify the "x axis", there should be a provision to specify the format of the "major / minor" tick "labels".

Or there could be an "on load" event for the item or something similar that allows for trapping the label for rotating etc.

Posted 27-Aug-19 4:30am

Gerry Schmitz

Comments

Member 14560567 27-Aug-19 12:16pm

I did this:

Dim x As System.DateTime
and inside of 'While' =
x = reader.GetString("hora")

but this is the error now=

Error 1 Overload resolution failed because no accessible 'Add' can be called with these arguments:
'Public Sub Add(x As Double, y As Double)': Conversion from 'Date' to 'Double' requires calling the 'Date.ToOADate' method.
'Public Sub Add(x() As Double, y() As Double)': Value of type 'Date' cannot be converted to '1-dimensional array of Double'.
'Public Sub Add(x() As Double, y() As Double)': Value of type 'Single' cannot be converted to '1-dimensional array of Double'.

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Member 14560567 · Accepted Answer · 2019-08-27T07:43:00

the solution is:

Dim list1 = New PointPairList()
Dim y As Single
Dim x As Single
Dim c As Date

      If reader.Read Then
                While reader.Read()
                    y = Replace(reader.GetString(3), ".", ",")
                    c = Convert.ToDateTime(reader.GetString(11))
                    x = c.ToOADate()
                    list1.Add(x, y)
                End While
                reader.Close()
            End If

it works!!!! (Y) thanks so much!