Re: problem plotting "N-d object"

[Ben Abbott]

On Feb 17, 2012, at 10:15 AM, Sergei Steshenko wrote:

> Hello,
> 
> here is a screen session:
> 
> "
> octave:3> foo(1,1,:) = [1 2 3]
> foo =
> 
> ans(:,:,1) =  1
> ans(:,:,2) =  2
> ans(:,:,3) =  3
> 
> octave:4> plot(foo(1,1,:));
> error: transpose not defined for N-d objects
> error: called from:
> error:   
> /home/qemu/AFSWD/20111122/octave-3.4.2/share/octave/3.4.2/m/plot/private/__plt__.m
>  at line 179, column 8
> error:   
> /home/qemu/AFSWD/20111122/octave-3.4.2/share/octave/3.4.2/m/plot/private/__plt__.m
>  at line 104, column 17
> error:   
> /home/qemu/AFSWD/20111122/octave-3.4.2/share/octave/3.4.2/m/plot/plot.m at 
> line 194, column 9
> octave:4> plot(foo(1,1,:)(:));
> octave:5>             
> 
> ".
> 
> I don't understand why 'octave' complains about N-d objects - to me 
> "foo(1,1,:)" looks like a 1-d object. Because the first two of the three 
> indexes are fixed in the expression.
> 
> 
> And adding "(:)" solves the problem.
> 
> Just wondering - should it be that hard for end user ? Does Matlab behave the 
> sane way ?
> 
> Thanks,
>   Sergei.

For either plot(foo) or plot(foo(1,1,:), Matlab gives ...

        plot (foo)
        Error using plot
        Data may not have more than 2 dimensions

Even so, maybe an appropriate solution is to check if the numberic inputs have 
ndim > 2 and attempt to apply squeeze before throwing an error ?

If you like this idea, please open a feature request in the tracker.

        https://savannah.gnu.org/bugs/?group=octave

Ben