1891928: PercentageAxis (1891921: Enhanced LogarithmicAxis)

[mhilpert]

I wrote an enhanced LogarithmicAxis and a PercentageAxis that is suitable for financial charts:

[1891921] Enhanced LogarithmicAxis
With customizable logarithmic bases and tick label factors.

[1891928] PercentageAxis
Useful for financial charts.

Here's an example what PercentageAxis can do:

http://sourceforge.net/tracker/download ... aid=772905
(You need to click the link. Does anybody know how to display an image directly? The

Short explanation: the arithmetic view (bottom image) could lead to the opinion, that the chart increased significantly during the last 10-15 days, but that's not the case - it rose, but not as much as the image demonstrates. In fact, the chart didn't increase much more compared to the former (November till December) - and the percentage scaling (top image) shows this much more accurate. Read on at Price Scaling (StockCharts.com).[/url]

[mhilpert]

I updated the sources of the 2 axes to work with JFreeChart 1.0.0/1.0.1 and uploaded them to the corresponding RFE's:

a) MyLogarithmicAxis.java for JFreeChart 1.0.0-rc1 ([772898] Enhanced LogarithmicAxis)
b) PercentageAxis.java for JFreeChart 1.0.0-rc1 ([772905] PercentageAxis)

Note: if you use Java < 1.5, just remove the generics ("<...>") and annotations ("@Override") in the source.

[blutfink]

It appears to me that this enhanced version of LogarithmicAxis will not work properly if the graphed values are below 1 (still positive though). In this case, the scale will be distorted. If I multiply my data to values above 1, the problem does not appear and the graphs are identical to those obtained with the original version of LogarithmicAxis.

See example below. The upper image is made with the enhanced version, the lower is made with the original version.

Code: Select all

LogarithmicAxis xAxis = new MyLogarithmicAxis("...");

Code: Select all

LogarithmicAxis xAxis = new LogarithmicAxis("...");

The data and the rest of the code are exactly the same.

[blutfink]

As I see it now, this new LogarithmicAxis isn't designed to be used as a horizontal axis yet -- only as a vertical axis. Seems like I have to modify the original code myself.

[JoeShmoe]

Hello,

How did you guys create another set of labels (top + bottom) for X-Axis? I need to do the same ...

Thanks,
Joe.

[rantfoil]

This logarithmic axis provided by mhilpert is fantastic.

One thing that I noticed with both JFreeChart is that it works well to chart any numbers below 1 as well, thanks to what is happening in adjustedLog10() method... or in mhilpert's fix, adjustedLog() which properly handles different bases.

But java2DToValue doesn't properly convert java2d values back to plot values because it assumes all values shown are greater than logBase.

Here's a method you can use in your versions that properly does conversion back...

Code: Select all

    public double java2DToValue(double java2DValue, Rectangle2D plotArea, RectangleEdge edge) {
        Range range = getRange();

        double axisMin = switchedLog(range.getLowerBound());
        double axisMax = switchedLog(range.getUpperBound());

        double plotMin = 0.0;
        double plotMax = 0.0;
        if (RectangleEdge.isTopOrBottom(edge)) {
            plotMin = plotArea.getX();
            plotMax = plotArea.getMaxX();
        }
        else if (RectangleEdge.isLeftOrRight(edge)) {
            plotMin = plotArea.getMaxY();
            plotMax = plotArea.getMinY();
        }
        

        double retval;
        	
        if (isInverted()) {
        	retval = adjustedPow(axisMax
	                 - ((java2DValue - plotMin) / (plotMax - plotMin)) * (axisMax - axisMin));
          
        } else {
        	retval = adjustedPow(axisMin
    				+ ((java2DValue - plotMin) / (plotMax - plotMin)) * (axisMax - axisMin));
        }
        
        return retval;
        
    }//translateJava2DtoValue()


    public double adjustedPow(double val) {
    	boolean negFlag = false;
    	if (val < 0.0) {
    		negFlag = true;
    		val = -val;
    	}
    	
    	double retval = 0;
    	if (val > 0 && val < 1) {
    		retval = (Math.pow(logBase, val+1) - logBase)/(logBase-1); 
    	}
    	else if (val >= 1) {
    		retval = Math.pow(logBase, val);
    	}
    	return (negFlag) ? -retval : retval;
    }

[mhilpert]

@blutfink: sorry, I just needed the vertical axis, so far. The next version that I will update these days will have the corresponding refreshTicksHorizontal().

@rantfoil: I added your changes to my custom LogarithmicAxis. It didn't change my logarithmic charts but obviously java2DToValue() also needs the log base independent switchedLog() call instead of the standard switchedLog10().

I'm fighting with some tick label overlapping for a few of my logarithmic charts. I will upload a new version of both MyLogarithmicAxis and PercentageAxis soon with your changes incorporated.

If only David would finally integrate those classes in the standard API, I wouldn't have to fix many of those issues and change them for new JFreeChart versions due to changed APIs or (silently) changed implementations.

[lgarcia3]

This question is for blutfink. How did you make your x axis come out like that? With all the values less than 0 showing up on the tick labels and the vertical lines for those values also there?
See, I have a log plot with values between 0.001 and 1 and I only get those two values on my plot and nothing else to show. My client wants to see values in bewteen to have some reference; but I cannot make it work. Any code would be helpful too.
Thanks!

[evan]

@blutfink: sorry, I just needed the vertical axis, so far. The next version that I will update these days will have the corresponding refreshTicksHorizontal().

@rantfoil: I added your changes to my custom LogarithmicAxis. It didn't change my logarithmic charts but obviously java2DToValue() also needs the log base independent switchedLog() call instead of the standard switchedLog10().

I'm fighting with some tick label overlapping for a few of my logarithmic charts. I will upload a new version of both MyLogarithmicAxis and PercentageAxis soon with your changes incorporated.

If only David would finally integrate those classes in the standard API, I wouldn't have to fix many of those issues and change them for new JFreeChart versions due to changed APIs or (silently) changed implementations.

Hi mphilpert,

Any update on the implementation of horizontal(i.e. domain) axis of this?

It's a bit annoying that LogarithmicAxis behaves differently for domain axis so that data can't be displayed with ticks as ...10^-1, 10^0, 10^1, 10^2....

[mhilpert]

I added a new version of MyLogarithmicAxis/PercentageAxis that overwrites refreshTicksHorizontal() which should do the trick. This is untested as I don't need this. If only it would be integrated into JFreeChart, as other people also like this functionality ...

[evan]

I added a new version of MyLogarithmicAxis/PercentageAxis that overwrites refreshTicksHorizontal() which should do the trick. This is untested as I don't need this. If only it would be integrated into JFreeChart, as other people also like this functionality ...

Thanks mhilpert.

I've tried out your latest version of MyLogarithmicAxis, unfortunately, it still doesn't seem working for horizontal axis....

[mhilpert]

You can still achive the same by setting the vertical axis as logarithm axis, set orientation to horizontal, and place the y axis at right/bottom. The result will look like the x axis is the logarithm axis.

[mhilpert]

I finally posted the axes as patches on sourceforge:

[1891921] Enhanced LogarithmicAxis

[1891928] PercentageAxis

In addition, both axes unifiy the two refreshTicksVertical()/refreshTicksHorizontal() and offer new superscript exponents for the tick labels.

[mhilpert]

And another one looking for this: Logarithmic scaling on a number axis