Category Item labels

[phamdinhnguyen]

My chart has large number of categories, ie > 600.
All category item labels are crowded over one another resulting in unreadable blacken texts.

Is there a (simple) way to:
a) display category labels at a fixed interval, say one label for each 30 categories, and
b) obviously, need to preserve the chart with all 600 categories.
Thanks
phamdinhnguyen

[Clemens]

I also have a chart which a huge number of categories. For me it's important to have all category labels readable, so I put the chart into a scrollpane. After a while of investigation I found out one way it works fine for me. Have a look at my code, maybe it helps:

Code: Select all

//		calculate preferred size for chart panel
int size = this.m_analysis.getColKeys().size() * MINIMUM_CATEGROY_SIZE;
int width = ChartPanelConstants.DEFAULT_WIDTH;
int height = ChartPanelConstants.DEFAULT_HEIGHT;
int minWidth = ChartPanelConstants.DEFAULT_MINIMUM_DRAW_WIDTH;
int minHeight = ChartPanelConstants.DEFAULT_MINIMUM_DRAW_HEIGHT;
int maxWidth = ChartPanelConstants.DEFAULT_MAXIMUM_DRAW_WIDTH;
int maxHeight = ChartPanelConstants.DEFAULT_MAXIMUM_DRAW_HEIGHT;
//		find category axis
if (m_chart.getCategoryPlot().getOrientation().equals(PlotOrientation.HORIZONTAL)) {
	height = size;
	minHeight = size;
	maxHeight = size;
	width = 20;
} else {
	width = size;
	minWidth = size;
	maxWidth = size;
	height = 20;
}
// 		create chart panel with calculated size
cp =
	new ChartPanel(
		m_chart,
		width,
		height,
		minWidth,
		minHeight,
		maxWidth,
		maxHeight,
		true,
		false,
		false,
		false,
		false,
		true);
m_scrollPane.getViewport().setView(cp);
//		margins are interpreted as factor of the category-axis size
//		so inherit them from the number of categories
m_chart.getCategoryPlot().getDomainAxis().setUpperMargin((double) 2 / size);
m_chart.getCategoryPlot().getDomainAxis().setLowerMargin((double) 2 / size);
this.add(m_scrollPane, BorderLayout.CENTER);

I use JFreeChart 0.9.16. My only problem, I still couldn't solve is, to limit th e length of the labels along the category axis. If a label is too long, I want to truncate it and put ... at the end of the label. Does someone have any ideas how to do that?

[david.gilbert]

See also this thread:

http://www.jfree.org/phpBB2/viewtopic.php?t=7745

[Clemens]

The answer in the mentioned thread is not very satisfying, because

• I cannot group the categories any more
• I'm not dealing with dates

But the scrolling solution is OK for me. Is there any possibility to limit the length of the category labels - some kind of renderer would be nice

[phamdinhnguyen]

Clemens,

Have you tried to change the orientation of your category labels?
I had the same issue, and this is my simple customization for my chart that has too many category labels as well as being long.

private void customizeChart(Parms localParm)
{
localParm.oChart.setBackgroundPaint(Color.getHSBColor(178, 201, 6));
localParm.oPlot = localParm.oChart.getCategoryPlot();
localParm.oAxis = localParm.oPlot.getDomainAxis();
localParm.oAxis.setCategoryMargin(0.25); // twenty-five percent
localParm.oAxis.setLowerMargin(0.04); // four percent
localParm.oAxis.setUpperMargin(0.04); // four percent
localParm.oAxis.setMaxCategoryLabelWidthRatio(10);
if(localParm.oChartOrientation == PlotOrientation.VERTICAL)
localParm.oAxis.[b]setCategoryLabelPositions(CategoryLabelPositions.DOWN_90)[/b];
} // end customizeChart()

Good luck!
phamdinhnguyen

[Guest]

Please, could give me un example of code with the last API please?
Thanks.

[Guest]

please what is the MINIMUM_CATEGORY_SIZE constant? Is it in the jfreedoc?
and what is m_analysis? the dataset?

thanks.

[Guest]

I also would like to know what type is the argument in the JScrollPanel constructor in this case. thanks.