AxisX ItemLabel AutoRange Match DataPoints

[Aaron]

When the AxisX is displaying a Date and AutoRange is True, the ItemLabels that are displayed do not match/align with the DataPoints.  An example image is attached.  It is fine that some DataPoints do not have ItemLabels on the AxisX, but I would like the ItemLabels that are displayed to at least match up with a DataPoint.

This is the data source for the attached image:

Date	Value
9/11/2011	72.2213
9/18/2011	69.19848
9/25/2011	68.97124
10/2/2011	70.24254
10/9/2011	73.49885
10/16/2011	74.02531
10/23/2011	73.55423
10/30/2011	74.57479
11/6/2011	74.59043
11/13/2011	73.31678
11/20/2011	73.33056
11/27/2011	76.07927
12/4/2011	72.5183

Current ItemLabel Value Desired Value (actually in DataSet above)
10/01/2011 10/02/2011
10/21/2011 10/23/2011
11/10/2011 11/13/2011
11/30/2011 12/04/2011


Is there a way to force the AxisX ItemLabels to only display values for actual DataPoints in the DataSet?

[Nikolay]

Hello Aaron,

The axis AutoRange spaces the labels, depending on the available space - if you do not have enough space for, say, 10 labels but you have 10 Data Points, then it would not be possible to match each point with a label, unless you treat them as categories. Thus, the simplest solution for your scenario would be to map the DateTime values to XCategory, instead of XValue :

seriesMapping.ItemMappings.Add(new ItemMapping("Date", DataPointMember.XCategory));

This way you would have one label for each data point at all times.Hope this helps.

All the best,
Nikolay
the Telerik team

[Aaron]

Thank you for your response.

Would each DataPoint still be part of the same LineSeries (will each point be connected via a line from one to the other)?

Is it possible to "autorange" display the categories?  Ex: If I have 800 points, I don't want 800 ItemLabels.


If the "autorange" ability does not exist.  Is it possible to conditionally display categories labels?

[Nikolay]

Hello Aaron,

Yes, each DataPoint would be a part of the same Line series, the only difference is that when using categories the chart treats data as a sequence of non-numerical text labels. You couldn't sample the data down as each point is important, however, when you have a large data set and you do not wish to display all of the labels you could use the LabelStep property, which displays 1 from X number of labels :

RadChart1.DefaultView.ChartArea.AxisX.LabelStep = 10;

This way if you have, say 100 DataPoints, you would only have 10 labels, so you could avoid overlapping of the text. Alternatively, you could always use the manual axis range when needed.

Kind regards,
Nikolay
the Telerik team

[Aaron]

Thank you, using XCategory in conjunction with LabelStep is working well.  Now the only issue I'm having is that too many Major Tick Marks are visible, when the Label is not displayed the Major Tick Mark still is (image attached).

I tried setting the AxisX AutoRange to false and calculating the "Step" manually but I am having difficulty getting anything to display.  I believe this may be due to the XCategory being used instead of XValue.

I have thought of two solutions:
1.  Include the Major Tick Mark in the Label somehow.
2. Continue down the path of manually calculating the AxisX Step value.


What would you recommend?  Do you have any documentation around calculating the AxisX manually when an XCategory is being used?

[Aaron]

Petar Marchev,

I attempted to use the AxisX AddRange method, but now the values being displayed in the ItemLabels do not match the Point Marks they should be associated with (image attached).  The date range for the attached image should be 09/11/2011 through 12/04/2011.  I used the values AxisX.AddRange(1, 14, 2) and now, the last ItemLabel is displaying 10/23/2011 instead of 12/04/2011.

The AxisX is only displaying a tick and label for every other PointMark, but it is displaying values in the ItemLabels in order as if it was not skipping any PointMarks.

[Petar Marchev]

Hi Aaron,

It seems that the suggestion I made in my previous post is not applicable as it results in an incorrect chart. I apologize for this.

The only suggestion that I can make is to attach a handler to the SizeChanged event of the chart, find the ticks from the visual tree and hide them. I have prepared a simple project that demonstrates this and attached it to this post. Please explore it and let us know if this suggestion is a feasible solution for your current project.

Regards,
Petar Marchev
the Telerik team

[Aaron]

Petar Marchev,

When I run the solution you provided the output is what I'm looking for.  However, this solution does not work in my case.  The SizeChanged event is not raised for my chart consistently.  I am not binding to my chart a single time, the ItemsSource for my chart can be updated, the number of DataPoints can change, but the size of the chart will not change.

I have attempted to execute this code from the DataBound event, but the call to ChildrenOfTypeExtensions.ChildrenOfType<AxisXItem2D>(); does not return any results.

I have also attempted to execute this code in-line after the ItemsSource has been updated, but again the ChildrenOfTypeExtensions.ChildrenOfType<AxisXItem2D>(); does not return any results.

Why does this code only seem to work in the Chart's SizeChanged event?  Is there a way to get this to work in the Chart's DataBound event or the AxisX's RangeChanged event?  Is there a way to get this to work if executed manually/in-line after the ItemsSource is updated?

[Petar Marchev]

Hi Aaron,

I have attached a demo project to demonstrate how you can achieve this. The same code (the code from my previous attachment, that hides the ticks) is used but in the LayoutUpdated event. We unsubscribe from the LayoutUpdated event as soon as we have hidden the ticks we do not need. This is done in order to avoid a layout exception and performance consideration (this event is being raised many times, and we do not want to do the same thing over and over again).

It is possible that this code (the HideBetweenTicks method) is executed before the ticks have been generated. This is the reason you were not able to find this panel.

Check out the project and see if you can adopt this to your app.

All the best,
Petar Marchev
the Telerik team