|
 Bubbles Size Issue |
| Posted by Rick on Feb-22-2012 10:05 |
|
Hi Peter,
Sometimes when charting Bubble Charts, the Bubbles are too Big o too Small depending on the values of Y axis, X Axis and the Z values used (for example when mixing thousand values with percentages values). I know this is normal because the values passed to the chart.
# The XYZ points for the bubble chart
$dataX0 = array(1700, 3000, 1000, 17000);
$dataY0 = array(160, 690, 160, 750);
$dataZ0 = array(0.52, 0.105, 0.88, 0.140);
$dataX1 = array(0.500, 0.1000, 0.1300);
$dataY1 = array(40, 58, 85);
$dataZ1 = array(140, 202, 840);
$dataX2 = array(170, 300, 100, 170);
$dataY2 = array(16000, 6900, 1600, 7500);
$dataZ2 = array(52, 105, 88, 140);
$LayObj = $c->addScatterLayer($dataX0, $dataY0, "A", GlassSphere2Shape, 15, 0xff3333);
$LayObj->setSymbolScale($dataZ0);
$LayObj = $c->addScatterLayer($dataX1, $dataY1, "B", GlassSphere2Shape, 15, 0x0000ff);
$LayObj->setSymbolScale($dataZ1);
Is there any way to always have a Bubbles correctly showed in the chart according to the Z values?
I use to multiply or divide the Z values depending on the X/Y values but is not always work as I expect. Is there a better way to do this? |
| Re: Bubbles Size Issue |
| Posted by Peter Kwan on Feb-23-2012 02:01 |
|
Hi Rick,
I believe by default, in a bubble chart, the z values are in pixel units (unless your code explicitly used the XAxisScale or YAxisScale constant to change it to x or y axis units). So z=140 means the bubble is 140 pixels in diameter. It does not matter what are the values in the x or y axis or what are your x and y data values.
So in your case, regardless of what are the (x, y) values, you can just set the z value to a reasonable ratio of your plot area size in pixels. For example, if your plot area size is 600 x 400 pixels, and you would like to largest bubble to be around 20% of the width or height (whichever is smaller) of the plot area, then you can scale your z value so that the largest value is 80.
For example:
$scaleFactor = 80.0 / max($dataZ);
for ($i = 0; $i < count($dataZ); ++$i) $dataZ[i] = $dataZ[i] * $scaleFactor;
Hope this can help.
Regards
Peter Kwan |
| Re: Bubbles Size Issue |
| Posted by Rick on Feb-23-2012 03:18 |
|
| Thanks Peter |
|
Forum Home
Search
Message List
Post Message