Contour plot, fill color and logarithmic scale

Sep 19, 2013 at 2:42 PM
Hi everybody !

I'm using Oxyplot as a library for .Net framework 4.0, in VB Express 2010 environment.
I'm trying to make contour plots and my questions are the following.
  • Is it possible to have a logarithmic scale for the third axis ? If it is, what's the way to do it ?
  • Is it possible to fill the gap between contour levels ?
Thank you.

NHRL
Coordinator
Sep 20, 2013 at 7:10 AM
You can set the ContourLevels property of the ContourSeries.
Currently, it is not possible to fill the gap between the contour levels.
But you can add a HeatMapSeries before the ContourSeries - see the examples.
If you use a RangeColorAxis, I think you can get almost the same result.
Sep 20, 2013 at 8:41 AM
Thank you objo for you answer.
Indeed, I set the ContourLevels to {1,10,100,1000}, creating a logarithmic scale.

Concerning the HeatMapSeries, I did not managed to use it.
I have the following error :
La référence d'objet n'est pas définie à une instance d'objet.
with the following code :
Dim Plotmodel1 As New PlotModel
        Plotmodel1.Title = "Atlas de vagues - " & ComboBox1.SelectedItem
        Dim linearAxis1 As New LinearAxis()
        linearAxis1.Position = AxisPosition.Bottom
        linearAxis1.Title = "Tz (s)"
        linearAxis1.MajorGridlineStyle = LineStyle.Solid
        linearAxis1.MinorGridlineStyle = LineStyle.LongDash
        Plotmodel1.Axes.Add(linearAxis1)
        Dim linearAxis2 As New LinearAxis()
        linearAxis2.MajorGridlineStyle = LineStyle.Solid
        linearAxis2.MinorGridlineStyle = LineStyle.LongDash
        linearAxis2.Title = "Hs (m)"
        Plotmodel1.Axes.Add(linearAxis2)
        Dim contourSeries1 As New ContourSeries()
        Dim heatMapSeries1 As New HeatMapSeries()

        heatMapSeries1.X0 = tz_ss(0)
        heatMapSeries1.X1 = tz_ss(UBound(tz_ss, 1))
        heatMapSeries1.Y0 = hs_ss(0)
        heatMapSeries1.Y1 = hs_ss(UBound(hs_ss, 1))
        heatMapSeries1.Data = prob_ss

        contourSeries1.ColumnCoordinates = tz_ss
        contourSeries1.ContourLevels = {1, 10, 100, 1000, 10000}
        contourSeries1.LineStyle = LineStyle.Solid
        contourSeries1.StrokeThickness = 5

        contourSeries1.ContourColors = {OxyColors.Aquamarine, OxyColors.Aqua, OxyColors.CadetBlue, OxyColors.Blue, OxyColors.Black}
        contourSeries1.Data = prob_ss
        contourSeries1.RowCoordinates = hs_ss

        Plotmodel1.Series.Add(heatMapSeries1)
        Plotmodel1.Series.Add(contourSeries1)
        Plotmodel1.Background = OxyColors.White
        Plotmodel1.PlotAreaBackground = OxyColors.White


        Plot1.Model = Plotmodel1
If I add only the contourseries1 to the Plotmodel1, it works. But with the heatMapSeries1, it fails.
Sep 20, 2013 at 2:00 PM
In addition to my previous post, I can tell you that :
  • On my oxyplot version, the method "Add" doesn't exist for the "Data" method of "Heatmapseries"
  • The version of Oxyplot I use seems to be different of the one used for the exemple (?)
  • I cannot reproduce the simple examples of Heatmapseries that are provided in the examplebrowser..
Do you have any idea ?
Oct 1, 2013 at 8:45 AM
Does anybody have an idea ?
Coordinator
Oct 1, 2013 at 8:09 PM
Did you check the real source code for the examples? I see that the generated code is not correct for Array properties.
I added an issue on this: https://oxyplot.codeplex.com/workitem/10083
thanks!
Coordinator
Oct 1, 2013 at 8:51 PM
the issue with the arrays should now be fixed
Oct 2, 2013 at 11:35 AM
Hi objo.

Thank you for your answer. Unfortunately, it did not solve my problem.
Actually, I code in VB.net, not in C#.
I'm trying to translate the example code from C# to VB.net, but I have errors.
Particularly, I don't know how to translate this line :
heatMapSeries1.Data = new Double[100, 100];
And I think this line is important.

Do you have any idea ?
Coordinator
Oct 2, 2013 at 11:42 AM
Oct 2, 2013 at 12:05 PM
Ok, the translation in VB.net should be :
heatmapseries1.Data = New Double(2, 2) {{1, 2, 3}, {3, 2, 1}, {1, 1, 1}}`
Now, here is my entire code :
Plotmodel1.Title = "Atlas de vagues - " & ComboBox1.SelectedItem
        Dim linearColorAxis1 As New LinearColorAxis()
        linearColorAxis1.HighColor = OxyColors.Gray
        linearColorAxis1.LowColor = OxyColors.Black
        linearColorAxis1.Position = AxisPosition.Right
        Plotmodel1.Axes.Add(linearColorAxis1)
        Dim linearAxis1 As New LinearAxis()
        linearAxis1.Position = AxisPosition.Bottom
        linearAxis1.Title = "Tz (s)"
        linearAxis1.MajorGridlineStyle = LineStyle.Solid
        linearAxis1.MinorGridlineStyle = LineStyle.LongDash
        linearAxis1.Position = AxisPosition.Bottom
        Plotmodel1.Axes.Add(linearAxis1)
        Dim linearAxis2 As New LinearAxis()
        linearAxis2.MajorGridlineStyle = LineStyle.Solid
        linearAxis2.MinorGridlineStyle = LineStyle.LongDash
        linearAxis2.Title = "Hs (m)"
        Plotmodel1.Axes.Add(linearAxis2)

        Plotmodel1.Background = OxyColors.White
        Plotmodel1.PlotAreaBackground = OxyColors.White

        Dim heatmapseries1 As New HeatMapSeries
        heatmapseries1.X0 = 0.5
        heatmapseries1.X1 = 10.5
        heatmapseries1.Y0 = 0.5
        heatmapseries1.Y1 = 15.5
        heatmapseries1.Data = New Double(2, 2) {{1, 2, 3}, {3, 2, 1}, {1, 1, 1}}

        Plotmodel1.Series.Add(heatmapseries1)

        Plot1.Model = Plotmodel1
But the error remain. Actually, visual studio doesn't return any error, but my plot is empty with the following text in red :
OxyPlot paint exception : La référence d'objet n'est pas définie à une instance d'objet.
in english :
OxyPlot paint exception : object reference not set to an instance of an object
Thank you again.

NHRL
Oct 8, 2013 at 8:52 AM
Does anybody have an idea ?

I find OxyPlot is a wonderful toolbox, but it's a pity that I can't use its full capabilities..