Re: Got any tips for drawing 2d graphs with error bars, symbols,etc?

Hi Bill and all,

Bill Hibbard wrote:
Hi Frank,

Can anyone explain the threshold effect of the negative value for the pBars
- shouldn't any negative value cause the desired lines from below y=0 up to
the data point?


The key point is to get the right relation between the
-0.1 in pBars.coordinates, and the values passed to the
setRange() method for yMap and pBarScaleMap. For example,
I think the following work:

  yMap.setRange(0.0, 40.0);
  pBarScaleMap.setRange(0.0, 2.0);

I suspect the general relation is something like:

  pBars.coordinates = new float[] {0.0f, 0.0f, 0.0f,  0.0f, x, 0.0f};
  yMap.setRange(0.0, y);
  pBarScaleMap.setRange(0.0, x * y / 2.0);

But I could be wrong. Please experiment (and Ugo please
correct me if I'm wrong).


my approach would be: try it out!

Though I did use the bars some time ago, today I think I'd use Linear2DSets for that.

Perhaps we ought to have a (DisplayRealType)Display.ErrorBar? If there exists error propagation in VisAD, there there could/should exist some handsome way of visualisaing that. I'm really thinking of standards error bars, here the ascii version:
  ___                                      ___
   |                                        |
   |                                        |
   x        or even with sx and sy:      |--x--|
   |                                        |
  _|_                                      _|_

Cheers,

Ugo