How to get x, y data in chart script (beforeDrawLegendItem)

I have this BIRT report with a scatter chart. 
I need to customize the legend labels so that they show both x and y values (i.e., both value and category). 
I know how to get to the label to get the current text (which is the grouping text), but I could not find anywhere how to get to the data point associated with the current legend label being drawn. 
 
Here is what I'd like to do in my chart script (please note the "todo:" comments): 
 
<pre class='_prettyXprint _lang-auto _linenums:0'>
function beforeDrawLegendItem( lerh, bounds, icsc )
{
var sLocation = lerh.getLabel().getCaption().getValue();

var xValue = "x"; //todo: somehow get the "x" value;
var yValue = "y"; //todo: somehow get the "y" value;

var sFinal = sLocation + " (" + yValue + ", " + xValue + ")";
lerh.getLabel().getCaption().setValue( sFinal );
}
</pre>
 
Thank you very much in advance for any clues.

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Comments

JasonW

Take a look at this example. It loads a javascript array that is then read in the legend script.

Jason

dstoian

Thanks, Jason, for the quick reply. I can see it working in the report you've attached, but when I put similar code in my report I get an exception on the line where I try to access the array inside beforeDrawLegendItem(). 
 
Please see below, the line marked by comment. 
This is my script now: 
 
<pre class='_prettyXprint _lang-auto _linenums:0'>

y=[];

function beforeDrawLegendItem( lerh, bounds, icsc )
{
var sLocation = lerh.getLabel().getCaption().getValue();

//exception on next line: "y" array is undefined
var yValue = y[lerh.getDataIndex()][0];
var xValue = y[lerh.getDataIndex()][1];
var sFinal = sLocation + " (" + yValue + ", " + xValue + ")";
lerh.getLabel().getCaption().setValue( sFinal );
}

function beforeDrawDataPointLabel( dph, label, icsc )
{
var x=[];
x[0]=dph.getOrthogonalValue();
x[1]=dph.getBaseValue();
y[dph.getIndex()]=x;
}
</pre>
 
The error reads: 
An error occurred while viewing the report. Cannot view report. Cause: TypeError: Cannot read property "0.0" from undefined at line 63 of chart script:''. 
 
It all looks simple, but I can't figure why...

JasonW

try using the parseInt on the array index:

var y=[];

function beforeDrawLegendItem( lerh, bounds, icsc )
{
var newstr=y[parseInt(lerh.getDataIndex())][0] +"-"+ y[lerh.getDataIndex()][1];
lerh.getLabel().getCaption().setValue(newstr)
}

function beforeDrawDataPointLabel(dph, label, icsc)
{
var x=[];
x[0]=dph.getOrthogonalValue();
x[1]=dph.getBaseValue();
y[parseInt(dph.getIndex())]=x;
}

Jason

dstoian

I've tried what you suggested, Jason (using parseInt() on the index of the array. Still, the same error: "Cannot read property... from undefined".

But, I think the exception is that the array is undefined... I don't understand the difference: same code works in your example report.

Thanks.

JasonW

Put something like this in (Or debug the reprort):

function beforeDrawDataPointLabel( dph, label, icsc )
{
var x=[];
x[0]=dph.getOrthogonalValue();
x[1]=dph.getBaseValue();
y[dph.getIndex()]=x;
importPackage( Packages.java.io );
out = new PrintWriter( new FileWriter( "c:/test/chartevents.txt", true ) );
out.println( y[parseInt(dph.getIndex())][0] );
out.close();
}

dstoian

Jason, 
 
I've written out data to a log as you suggested, and here's what I found out: I have 3 data points which have identical coordinates, and somehow, in beforeDrawDataPoint event, all these 3 points get an index of 0 (zero). 
 
That's why in beforeDrawLegendItem I was getting the exception. 
 
I am confused as to why I don't see 10 indexes (0 to 9) because that's how my data is... 
 
This is my log: 
<pre class='_prettyXprint _lang-auto _linenums:0'>
beforeDrawDataPoint: dph.getIndex()=0; 117.46, 112.08
beforeDrawDataPoint: dph.getIndex()=0; 117.46, 112.08
beforeDrawDataPoint: dph.getIndex()=1; 122.61, 97.46
beforeDrawDataPoint: dph.getIndex()=0; 117.46, 112.08
beforeDrawDataPoint: dph.getIndex()=2; 115.93, 78.46
beforeDrawDataPoint: dph.getIndex()=3; 117.31, 88.35
beforeDrawDataPoint: dph.getIndex()=4; 117.64, 91.33
beforeDrawDataPoint: dph.getIndex()=5; 121.09, 83.96
beforeDrawDataPoint: dph.getIndex()=6; 117.29, 85.96
beforeDrawDataPoint: dph.getIndex()=7; 115.69, 91.4
beforeDrawLegendItem: lerh.getDataIndex()=0
beforeDrawLegendItem: lerh.getDataIndex()=1
beforeDrawLegendItem: lerh.getDataIndex()=2
beforeDrawLegendItem: lerh.getDataIndex()=3
beforeDrawLegendItem: lerh.getDataIndex()=4
beforeDrawLegendItem: lerh.getDataIndex()=5
beforeDrawLegendItem: lerh.getDataIndex()=6
beforeDrawLegendItem: lerh.getDataIndex()=7
beforeDrawLegendItem: lerh.getDataIndex()=8
</pre>
 
I'll be using my own counter to replace those indexes: that's already tested and it works. 
Thanks for all the help.

JasonW

Any chance you could post the report?

dstoian

Jason, 
 
I can post the script here, but if you want I can send you the report in an email... it's complicated, though, you won't be able to run it. 
 
Here's how the script for the chart looks now (working): 
<pre class='_prettyXprint _lang-auto _linenums:0'>
yarr=[];
npts=0;
nleg=0;

function beforeDrawDataPoint( dph, fill, icsc )
{
var x=[];
npts=npts+1;
x[0]=dph.getOrthogonalValue();
x[1]=dph.getBaseValue();
yarr[npts-1]=x;
}

function beforeDrawLegendItem( lerh, bounds, icsc )
{
nleg=nleg+1;
var sLocation = lerh.getLabel().getCaption().getValue();
var yValue = yarr[nleg-1][0] + "%";
var xValue = yarr[nleg-1][1] + "%";
var sFinal = sLocation + " (" + yValue + ", " + xValue + ")";
lerh.getLabel().getCaption().setValue( sFinal );
}
</pre>

JasonW

I was just wondering why the index did not work.

dstoian

<blockquote class='ipsBlockquote' data-author="JasonW">I was just wondering why the index did not work.</blockquote>
 
I think it's pretty clear from my post with the log above (the same bug will show up in your example report if you have 3 points with the same coordinates). 
 
Data points with same coordinates get assigned same indexes (I had 10 data points to plot), so indexes went from 0-7 in "beforeDrawDataPoint", whereas in "beforeDrawLegendItem" the indexes went form 0-8... 
 
Why aren't there 10 indexes as one would expect, from 0-9 ? 
 
Thanks.

JasonW

Do you have multiple series or grouping?
If I use three datapoints with same y vals I still get 0,1,2 with the indexes.

dstoian

Oh, yes, I do have grouping, as can be seen in the attached image... I hope I'm not doing anything wrongly (as I might very easily

)