Adding custom axis titles for Bubble Chart

Question

How to add custom axis titles (for each group of axis values) as shown in the attached figure to a bubble chart ?
- Sen

Answer 1

I'm trying to do essentially the same thing with a LineChart and I think I've got part of it figured out.
I've subclassed CategoryAxis and overridden reduceLabels to return only certain labels (the "group" labels). Then I create a new axis by adding a LineSeries to the chart's <series> element with the new axis within the LineSeries. Then I have an AxisRenderer in the chart's horizontalAxisRenderers tag that refers to the new axis from within the LineSeries.
Subclassed axis:
    public class MonthCategoryAxis extends CategoryAxis
        public function MonthCategoryAxis()
            super();
        override public function reduceLabels(intervalStart:AxisLabel, intervalEnd:AxisLabel):AxisLabelSet
            var currentLabels:AxisLabelSet = this.getLabels(0); // Param is ignored by super class
            var newLabels:Array = []; // Labels to keep
            var label:AxisLabel;
            var previousLabel:AxisLabel;
            for (var i:int = 0; i < currentLabels.labels.length; i++)
                label = currentLabels.labels[i];
                if (i == 0) // Keep the first label
                    newLabels.push(label);
                else if (label.value.month != previousLabel.value.month)
                    // Only keep a label if the previous label has a different month
                    newLabels.push(label);
                previousLabel = label;
            // Return a new AxisLabelSet with just the labels we want
            var newLabelSet:AxisLabelSet = new AxisLabelSet();
            newLabelSet.labels = newLabels;
            return newLabelSet;
New series to create the subclassed axis in.
            <mx:LineSeries>
                <mx:horizontalAxis>
                    <charts:MonthCategoryAxis id="MonthAxis" labelFunction="calendarMonthAxisLabelFunction"/>
                </mx:horizontalAxis>
            </mx:LineSeries>
The AxisRenderer. canDropLabels must be "true".
            <mx:AxisRenderer axis="{MonthAxis}" canDropLabels="true" showLine="false" tickPlacement="none">
                <mx:labelRenderer>
                    <mx:Component>
                            <mx:Label width="100%">
                            <mx:Script>
                                <![CDATA[
                                override public function set data(axisLabel:Object):void
                                    this.text = outerDocument.getMonthLabel(axisLabel.value);
                                ]]>
                            </mx:Script>
                            </mx:Label>
                    </mx:Component>
                </mx:labelRenderer>
            </mx:AxisRenderer>