Move up a secondary y Axis and its series

Hello,
anyone can help me out on this one ?

If you look at the gif's attached, I have a secondary y Axis and I'm desperately trying to move up this y Axis and its series so that the series start value of 100 is aligned with the horizontal axis (and therefore aligned with the 0% value on the primary y Axis).

I've tried many things in a java Chart handler : changing the chart Scale min/max values in beforeGeneration(), changing the values of the DataSet by removing 100 in afterDataSetFilled(), etc... without success.

Really appreciate any help....
Fred

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bigFred

What I'm trying to do is the following :
in the beforeGeneration method, I calculate the max and the min of the series DataSet. With this values and a fixed number of axis ticks I want, I calculate the step, range between 2 ticks. And with this step, I finally calculate the difference between the total number of steps/2 and the number of steps from the origin to 100. It gives me the number I'll set in the field Min in the Scale : ...getScale().setMin(calc number)....
I have the feeling that somehow I reinvent the wheele, that this kind of algorithm should be done in the Chart engine. Either i didn't find it or we have no access to it.

Thanks if you have any idea for making this more simple.

mwilliams

Can you show me some sample data so I can try to recreate your chart? Or can you recreate the issue for me with the sample database or some other sort of source that I can use to run the report? Thanks!

bigFred

Thanks for looking at my problem. Attached is the CSV comma separated file chart_2_y_axis_data.txt containing all the data you need for my chart.

Note the following points :

1. - the xAxis category is build from column PtfDate,
- primary Bars yAxis from PtfPerf, BenchPerf, DiffPerf
- secondary Lines yAxis2 from PtfCumuPerf, BenchCumuPerf, DiffCumuPerf

2. In the chart, I set the xAxis Origin at Value 0

3. All axes have the Scale Step to Auto

mwilliams

What's your BIRT version?

bigFred

I have the chart engine 2.6.2

I think I'll come soon with a solution. I have to work on scal min, max, steps of both primary and secondary yAxis. I publish my temptative solution asap.
Thanks

bigFred

okay, I've got something. It works in the sense that I have my secondary axis centered at 1% (or 100 basis point), and the primary axis centered at 0%. I still have to work on the number of steps. 
 
Here is the code of my chart handler : 
 
public class GraphicalPerformanceChartEventHandler extends 
ChartEventHandlerAdapter { 
 
@Override 
public void beforeGeneration(Chart chart, IChartScriptContext icsc) { 
 
super.beforeGeneration(chart, icsc); 
if (chart instanceof ChartWithAxesImpl) { 
ChartWithAxesImpl chartWithAxis = (ChartWithAxesImpl) chart; 
 
Axis yAxis = chartWithAxis.getOrthogonalAxes(xAxis, true)[0]; 
Axis yAxis2 = chartWithAxis.getOrthogonalAxes(xAxis, true)[1]; 
 
 
// Get the bar series 
EList<SeriesDefinition> ySeriesDefn = yAxis.getSeriesDefinitions(); 
Series[] ySeries = yAxis.getRuntimeSeries(); 
 
//Get the line series 
EList<SeriesDefinition> ySeriesDefn2 = yAxis2.getSeriesDefinitions(); 
Series[] ySeries2 = yAxis2.getRuntimeSeries(); 
 
//Find the max for the y series DataSet 
Double max = getMaxSeriesValue(ySeries); 
Double max2 = getMaxSeriesValue(ySeries2); 
 
//Add gaps to axis up limits 
max = Math.ceil(max); 
max2 = Math.ceil(max2); 
 
//calculate half amplitude, different for the secondary y axis 
Double halfAxisAmplitude = max ; 
Double halfAxisAmplitude2 = max2 - 1.0; 
 
Double min = 0.0 - halfAxisAmplitude; 
Double min2 = 1.0 - halfAxisAmplitude2; 
 
yAxis.getScale().setMin(NumberDataElementImpl.create(min.doubleValue())); 
yAxis.getScale().setMax(NumberDataElementImpl.create(max.doubleValue())); 
 
yAxis2.getScale().setMin(NumberDataElementImpl.create(min2.doubleValue())); 
yAxis2.getScale().setMax(NumberDataElementImpl.create(max2.doubleValue())); 
} 
} 
 
private Double getMaxSeriesValue(Series[] ySeries2) { 
Double max = new Double(0.0); 
for (int i = 0; i < ySeries2.length; i++) { 
Number[] values = (Number[])ySeries2.getDataSet().getValues(); 
for (int j = 0; j < values.length; j++) { 
if(i == 0 && j == 0){ 
max = (Double)values[0]; 
} 
if((Double)values[j] > max){ 
max = (Double)values[j]; 
} 
} 
} 
return max; 
} 
}

mwilliams

Thanks for the update. I had messed around with trying to set a secondary axis and x-axis intersection in an easier way, and I didn't see one. What you've done is probably what you have to do to get this exactly how you want it. If I find anything simpler, I'll let you know. You could always log an enhancement request for this in the eclipse.org/birt bugzilla to have a setting where the x-axis intersects the secondary axis.

bigFred

Thanks, actually the java handler I've programmed works pretty well now. I just had to add a calculation for the max + a gap, depending on the max series values that may have different decimal value. And also I needed to adjust the primary y Axis as well in order to center it to 0% following the max series value calculated before. 
 
Here is my final code version. Might help other BIRT developper : 
 
<pre class='_prettyXprint _lang-auto _linenums:0'>/**
* Handle the position of both y axis : the primary axis is centered to 0%
* and the secondary y axis is centered to 1% (100 basis point)
* @param yAxis the primary y axis
* @param yAxis2 the secondary y axis
* @param ySeries the primary y axis series
* @param ySeries2 the secondary y axis series
*/
private void handleVerticalAxisPosition(Axis yAxis, Axis yAxis2,
Series[] ySeries, Series[] ySeries2) {
//Find the max for the y series DataSet
Double max = getMaxSeriesValue(ySeries);
Double max2 = getMaxSeriesValue(ySeries2);

//Add gaps to axis up limits

Double maxWithGap = getMaxSeriesWithGap(max);
Double maxWithGap2 = getMaxSeriesWithGap(max2);

//calculate half amplitude, different for the secondary y axis
//the secondary y Axis is centerer on 1% (or 100 basis point) to the x axis
Double halfAxisAmplitude = maxWithGap ;
Double halfAxisAmplitude2 = maxWithGap2 - 1.0;

Double min = 0.0 - halfAxisAmplitude;
Double min2 = 1.0 - halfAxisAmplitude2;

yAxis.getScale().setMin(NumberDataElementImpl.create(min.doubleValue()));
yAxis.getScale().setMax(NumberDataElementImpl.create(maxWithGap.doubleValue()));

yAxis2.getScale().setMin(NumberDataElementImpl.create(min2.doubleValue()));
yAxis2.getScale().setMax(NumberDataElementImpl.create(maxWithGap2.doubleValue()));
}

/**
* Resize the max value with a gap.
* The rule applied here is to round to the first non 0 decimal :
* 0.037 -> 0.04, 3.4 -> 4
* @param max
* @return the max with the added gap
*/
private Double getMaxSeriesWithGap(Double max) {
int decimalIndex = 0;
while( max< 1.0 ) {
max = max * 10;
decimalIndex++;
}
max = Math.ceil(max)/Math.pow(10, decimalIndex);
return max;
}

/**
* Return the max value in the given series.
* @param ySeries
* @return the max value in the series
*/
private Double getMaxSeriesValue(Series[] ySeries) {
Double max = new Double(0.0);
for (int i = 0; i < ySeries.length; i++) {
Number[] values = (Number[])ySeries[i].getDataSet().getValues();
for (int j = 0; j < values.length; j++) {
if(i == 0 && j == 0){
max = (Double)values[0];
}
if((Double)values[j] > max){
max = (Double)values[j];
}
}
}
return max;
}</pre>