Heat map Custom Axis Y

Hello Jason,

I succeeded to integrate your chart with Heatmap Series to our application. (I have to tell that it was pretty easy). Now I need to make some "look and feel" customization according to our application requirements.

I need to display custom values on axis Y instead of displaying range of buckets.

Example : Let say I have 1000 buckets on axis Y and the real range is [-300 Voltage, 300 Voltage] and axis Y labels need to be displayed according given range.

I tried to implement IAxisValueConverter and to make binding of it on axis Y:

  <ms:Chart.YAxis>
    <ms:ChartAxis ValueConverter="{Binding AxisYValueConverter}" />
  </ms:Chart.YAxis>

But method AxisYValueConverter->GetAxisPlotPosition(object o) gets double[1000] and I don't know how to convert it to chart index.

Is there any way to display custom labels?

Thanks, Pavel

Hi Pavel,

It sounds like you are on the right track. Thanks for contacting us about this, custom axis converters for the heatmap is tricky due to the data points being arrays.

Here's a possible implementation based on what you want:

public class CustomAxisValueConverter : IAxisValueConverter
{
  private double _actualMinimum = -300;
  private double _actualMaximum = 300;
  private double _dataCount = 1000;

  public double GetAxisPlotPosition(object o)
  {
    if (o is float[])
    {
      return ((float[])o).Length;
    }
    if (o is int)
    {
      return (double)(int)o;
    }
    return (double)o;
  }

  public object GetDataObjectAt(double axisPosition)
  {
    double ratio = axisPosition / _dataCount;
    double actualRange = _actualMaximum - _actualMinimum;
    double actualPosition = actualRange * ratio + _actualMinimum;
    return actualPosition;
  }
}

If the object being plotted is an array, then you'll simply want to return the length of that array. Otherwise the object is most likely a numeric value which should be cast to a double as appropriate and returned.

In the other method, I divide and multiply the given value to convert it from a scale of 0-1000 to a scale of -300-300. These values are set as class fields which you may want to expose as properties so that they can be set in xaml, rather than being hard coded.

Let me know if you have further questions about this.

-Jason Fauchelle