In bubble chart can I use area rather than diameter to represent bubble size?

Hi, I noticed that in a bubble chart, the bubble size represents the diameter rather than the area. (I'm on BIRT 2.5.2). For example, a bubble with size 2 has 2 times the diameter than a bubble with size 1, making the first bubble 4 time bigger than the second. Can I make the bubble size represent area instead? I know I can simply take the square root of the values and feed them as bubble size but at the same time I need the label to display the original values correctly. I found an example that customizes labels with scripts here: <a data-ipb='nomediaparse' href='http://developer.actuate.com/community/forum/index.php?/topic/19874-customize-series-labels-in-bubble-chart/'>http://developer.actuate.com/community/forum/index.php?/topic/19874-customize-series-labels-in-bubble-chart/</a>. But the problem is, due to my development environment I cannot overwrite any onRender() events in my chart. Could somebody advise? Thanks.

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hanl1

Anybody ?

hanl1

Trying my luck one more time.. Is everybody okay with scaling by diameter/radius rather than area? As far as I understand that is generally considered a bad representation: <a data-ipb='nomediaparse' href='http://en.wikipedia.org/wiki/Bubble_chart#Choosing_bubble_sizes_correctly'>http://en.wikipedia.org/wiki/Bubble_chart#Choosing_bubble_sizes_correctly</a>

hanl1

Can anyone help with this please

donino

Hi,

I agree bubble charts are currently not usuable out of the box because of this issue. It is also unfortunate we can't natively display a label within bubbles.

By looking at the source code, it appears there would be only one line of code to change to fix the size of bubbles:

In class <a data-ipb='nomediaparse' href='http://grepcode.com/file/repo1.maven.org/maven2/org.eclipse.birt.runtime/org.eclipse.birt.runtime/4.3.1/org/eclipse/birt/chart/extension/render/Bubble.java/'>org.eclipse.birt.chart.extension.render.Bubble</a>:
<pre class="_prettyXprint">dSizePixel[i] = be.getSize( ) * dPointCoefficient;</pre>should be changed into (we just apply a square root on the size):
<pre class="_prettyXprint">dSizePixel[i] = Math.sqrt(be.getSize( )) * dPointCoefficient;</pre>May be you could fill an enhancement request for this. Pending this, it is possible to workaround the problem by doing the same in a render script of the chart, in "afterComputations" method. I hope it helps.

kclark

Can you file an enhancement request for this <a data-ipb='nomediaparse' href='http://eclipse.org/birt/phoenix/reportabug.php'>here</a>?