[Octave-bug-tracker] [bug #63033] "axis tight" includes x-data in limit calculation for which the y-data is NaN

[Rik]

Update of bug #63033 (project octave):

                Severity:              3 - Normal => 1 - Wish               
                Priority:              5 - Normal => 3 - Low                
                  Status:                    None => Confirmed              
                 Release:                   7.2.0 => dev                    
        Operating System:       Microsoft Windows => Any                    
                 Summary: axis tight does not ignore NaN => "axis tight"
includes x-data in limit calculation for which the y-data is NaN

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Follow-up Comment #1:

Confirmed.  Re-titling the bug report to be more precise about the issue.

Sample code


figure
plot (1:10, [1:9, NaN])
axis tight


The explanation is rather simple.  When Octave calculates limits for "axis
tight" it looks at each axis individually.  In the sample code, the x-data has
a minimum of 1 and a maximum of 10 so that is what Octave sets the axis limits
to.  Apparently Matlab also checks whether the corresponding y-value is
finite.  I tried two variations in Matlab and the limit is 9 in each case.


plot (1:10, [1:9, NaN])
plot (1:10, [1:9, Inf])


But, things aren't always straightforward even in Matlab.  This code produces
a line at 45 degrees from 1:9.  There are no line segments after x == 9, and
yet the limits of the plot are set at 1 and 11.


figure
plot (1:11, [1:9, NaN, 9])
axis tight


I know why it does that, but it still seems odd since there is no visual data
past 9.

Marking as a low priority since there are easy workarounds such as calling
xlim or axis with limits that look good to the programmer.



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