Multiple axes chart - baseline issue

Question

Hi all,
I'm currently working on charts (column, bar, line, ..) with
multiple axes (each for one series).
If negative amount values are shown in a chart, the baselines
(for zero values) appears
on different coordinates/levels.
As an example see the code listed below:
<?xml version="1.0"?>
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml">
<mx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
[Bindable]
public var expenses:ArrayCollection = new ArrayCollection([
{Month:"Jan", Profit:2000, Expenses:15},
{Month:"Feb", Profit:1000, Expenses:20},
{Month:"Mar", Profit:1500, Expenses:50},
{Month:"Apr", Profit:100, Expenses:-10}
]]>
</mx:Script>
<mx:Panel title="Column Chart">
<mx:ColumnChart id="myChart" dataProvider="{expenses}"
showDataTips="true">
<mx:horizontalAxis>
<mx:CategoryAxis dataProvider="{expenses}"
categoryField="Month"/>
</mx:horizontalAxis>
<mx:series>
<mx:ColumnSeries xField="Month" yField="Profit"
displayName="Profit">
<mx:verticalAxis>
<mx:LinearAxis id="v1"/>
</mx:verticalAxis>
</mx:ColumnSeries>
<mx:ColumnSeries xField="Month" yField="Expenses"
displayName="Expenses">
<mx:verticalAxis>
<mx:LinearAxis id="v2"/>
</mx:verticalAxis>
</mx:ColumnSeries>
</mx:series>
<mx:verticalAxisRenderers>
<mx:AxisRenderer placement="left" axis="{v1}"/>
<mx:AxisRenderer placement="right" axis="{v2}"/>
</mx:verticalAxisRenderers>
</mx:ColumnChart>
<mx:Legend dataProvider="{myChart}"/>
</mx:Panel>
</mx:Application>
I'm using Flex Builder 3.0.2 /Flex SDK 3.2.
Is this is a bug in flex?
Am i missing something in the mxml/as, or is there a solution
or workaround?
Any hints are highly appreciated.
Regards,
Matthias

Answer 1

The series both work fine on their own, of course, but when
you mix in a series with a negative value, it causes the "floating
columns" because the zero-points on the axes don't line up with
each other.
My suspicion is that this is expected behavior. This would
work with other column chart types (like stacked), as long as you
set allowNegativeForStacked to true (there's an example here:
http://livedocs.adobe.com/flex/3/html/help.html?content=charts_displayingdata_11.html).
But since you want clustered columns, it might be a problem.
If you think it is a bug, you can file one here:
http://bugs.adobe.com/jira
hth,
matt horn
flex docs