bugGNU Octave - Bugs: bug #37501, contourf incorrect when NaN...


bug #37501: contourf incorrect when NaN present on boundary

Submitted by:  Muhali <muhali>
Submitted on:  Thu Oct 4 12:14:45 2012  
Category: PlottingSeverity: 2 - Minor
Priority: 5 - NormalItem Group: None
Status: PostponedAssigned to: None
Originator Name: Open/Closed: Open
Release: devOperating System: GNU/Linux

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Wed Nov 16 19:24:21 2016, comment #6:

Bug is still present in contourf with the current development version of Octave.

Mike Miller <mtmiller>
Project Administrator
Wed Oct 31 16:34:13 2012, comment #5:

I notice that the 2-D data you are plotting with contourf has columns of NaN values on the far left and far right. If I strip out the NaNs the contourf plot looks exactly right.

It would be nice for Octave to behave better in this situation, but it is probably somewhat difficult to untangle. You might want to just use the workaround of removing the NaNs from your data.

For those interested, the file to check is scripts/plot/private/__contour__.m. Maybe we want to add a grid around the plotted data with a value that is always numerical and always small, such as -Inf, so that the contours will always close. Then when plotting we can remove the grid. This way the NaNs on the border will still close.

Rik <rik5>
Project Administrator
Thu Oct 4 15:41:45 2012, comment #4:

> Which graphics backend are you using?

For the attached figures fltk, but I see the same with gnuplot.

Muhali <muhali>
Thu Oct 4 15:35:29 2012, comment #3:

Which graphics backend are you using?

Michael Godfrey <godfrey>
Project Member
Thu Oct 4 14:51:09 2012, comment #2:

The original print figure, which was from my office machine, is attached (contour.png). On my home machine I cannot reproduce it either, and interestingly, not even when I use my office machine remotely.

But I can reproduce the contourf behavior,

with a similar straight line from NW to S as in contour.png (contourf.png attached).

(file #26699, file #26700)

Muhali <muhali>
Thu Oct 4 13:17:05 2012, comment #1:

I can't see the problem you're describing. Can you please post a few screenshots and images, perhaps annotating them with the precise problem? Also, can you test both gnuplot and fltk?

Jordi GutiƩrrez Hermoso <jordigh>
Project Administrator
Thu Oct 4 12:14:45 2012, original submission:

Using the attached foo.txt and doing

the plot figure is different from the print figure. The print figure seems to have the same error as the plot from using contourf.

Muhali <muhali>


(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach File(s):

Attached Files
file #26699:  contour.png added by muhali (73kB - image/png)
file #26700:  contourf.png added by muhali (113kB - image/png)
file #26697:  foo.txt added by muhali (31kB - text/plain)


Depends on the following items: None found

   bug dependencies.


Carbon-Copy List
  • -unavailable- added by mtmiller (Posted a comment)
  • -unavailable- added by rik5 (Posted a comment)
  • -unavailable- added by godfrey (Posted a comment)
  • -unavailable- added by jordigh (Posted a comment)
  • -unavailable- added by muhali (Submitted the item)

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    Follow 11 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Fri Nov 18 20:33:04 2016mtmillerDependencies-=>bugs #35033 is dependent
    Wed Nov 16 19:24:21 2016mtmillerSeverity3 - Normal=>2 - Minor
    Mon Jul 14 04:37:53 2014rik5Dependencies-=>bugs #42766 is dependent
    Wed Oct 31 16:34:13 2012rik5StatusNeed Info=>Confirmed
      Summarycontour produces incorrect print figure=>contourf incorrect when NaN present on boundary
    Thu Oct 4 14:51:09 2012muhaliAttached File-=>Added contour.png, #26699
      Attached File-=>Added contourf.png, #26700
    Thu Oct 4 13:17:05 2012jordighStatusNone=>Need Info
    Thu Oct 4 12:14:45 2012muhaliAttached File-=>Added foo.txt, #26697

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