matplotlib-users

[Matplotlib-users] Bug in imshow ?

[Eric E. <ems...@ob...>]

Hi,

2 issues:

1/ just to remind you that I am still looking for a solution to the 
previously
mentioned bug in imshow (in terms of aspect='preserve').

2/ I have another problem with imshow:

When I do for example:

figure(1)
axes([-0.1,0,0.8,0.8])
myima = rand(50,50)
imshow(myima)

then it works and shows me the array with the axes partly outside the window
since the origin for the X axis is < 0

However if I do:

figure(1)
axes([0,-0.1,0.8,0.8])
myima = rand(50,50)
 imshow(myima)

with this time the Y origin < 0:

then I get a SEGMENTATION FAULT

??
thanks for any help there...

Eric

-- 
===============================================================
Observatoire de Lyon                 ems...@ob...
9 av. Charles-Andre                      tel: +33 4 78 86 83 84
69561 Saint-Genis Laval Cedex            fax: +33 4 78 86 83 86
France               http://www-obs.univ-lyon1.fr/eric.emsellem
===============================================================

Re: [Matplotlib-users] Bug in imshow ?

[Xavier G. <gn...@ob...>]

Eric Emsellem a écrit :

> Hi,
>
> 2 issues:
>
> 1/ just to remind you that I am still looking for a solution to the 
> previously
> mentioned bug in imshow (in terms of aspect='preserve').
>
> 2/ I have another problem with imshow:
>
> When I do for example:
>
> figure(1)
> axes([-0.1,0,0.8,0.8])
> myima = rand(50,50)
> imshow(myima)
>
> then it works and shows me the array with the axes partly outside the 
> window
> since the origin for the X axis is < 0
>
> However if I do:
>
> figure(1)
> axes([0,-0.1,0.8,0.8])
> myima = rand(50,50)
> imshow(myima)
>
> with this time the Y origin < 0:
>
> then I get a SEGMENTATION FAULT
>
> ??
> thanks for any help there...
>
> Eric
>
I reproduce this bug with GTK and TKagg.

With DEBUG = 1  I get this (may help):

axes([0,-0.1,0.8,0.8])
myima = rand(50,50)
In [5]: imshow(myima)

FigureCanvasGTKAgg.draw
Segmentation fault

Xavier

Re: [Matplotlib-users] Bug in imshow ?

[John H. <jdh...@ac...>]

>>>>> "Eric" == Eric Emsellem <ems...@ob...> writes:

    Eric> 1/ just to remind you that I am still looking for a solution
    Eric> to the previously mentioned bug in imshow (in terms of
    Eric> aspect='preserve').

Hi Eric, thanks for the reminder.  Just to let you know, I'm away on
vacation until next week.  Because I am staying with my sister in an
apartment with an internet connection, I am tempted back to my old
ways and occasionally respond on the list.  But for the more difficult
questions and bugs, of which yours is one, which require more serious
coding and testing, I'm deferring until I have a proper setup to work
with.

Rest assured that I have flagged these many emails and will pick them
off as I can.

Cheers,
JDH

Re: [Matplotlib-users] Bug in imshow ?

[Eric E. <ems...@ob...>]

Hi John,
first:  please enjoy your vacation! don't worry about the bugs and 
annoying emails,
I know this is not a hotline!!

As for the second question about the ''illegal'' axis position: in fact 
I would like
VERY much that you are allowed to have your plots outside the window.
I know this sounds strange, but it is indeed very useful to analyse data,
although I am not intending to produce a scientific plot with axes outside
the window of course...
At some point I could send you the small wrapper/functions I wrote to 
display images using
imshow where I put some more options like: scaling, maximum axis, 
offsets etc....
This would then show you what I am trying to reach and in fact could
lead to a very different solution (within matplotlib instead).

Eric

John Hunter wrote:

>>>>>>"Eric" == Eric Emsellem <ems...@ob...> writes:
>>>>>>            
>>>>>>
>
>    Eric> 1/ just to remind you that I am still looking for a solution
>    Eric> to the previously mentioned bug in imshow (in terms of
>    Eric> aspect='preserve').
>
>Hi Eric, thanks for the reminder.  Just to let you know, I'm away on
>vacation until next week.  Because I am staying with my sister in an
>apartment with an internet connection, I am tempted back to my old
>ways and occasionally respond on the list.  But for the more difficult
>questions and bugs, of which yours is one, which require more serious
>coding and testing, I'm deferring until I have a proper setup to work
>with.
>
>Rest assured that I have flagged these many emails and will pick them
>off as I can.
>
>Cheers,
>JDH
>
>  
>

-- 
===============================================================
Observatoire de Lyon                 ems...@ob...
9 av. Charles-Andre                      tel: +33 4 78 86 83 84
69561 Saint-Genis Laval Cedex            fax: +33 4 78 86 83 86
France               http://www-obs.univ-lyon1.fr/eric.emsellem
===============================================================

Re: [Matplotlib-users] Bug in imshow ?

[John H. <jdh...@ac...>]

>>>>> "Eric" == Eric Emsellem <ems...@ob...> writes:

    Eric> 2/ I have another problem with imshow:

    Eric> When I do for example:

    Eric> figure(1) axes([-0.1,0,0.8,0.8]) myima = rand(50,50)
    Eric> imshow(myima)

    Eric> then it works and shows me the array with the axes partly
    Eric> outside the window since the origin for the X axis is < 0

Hmm, it never occurred to me that someone would be placing the axes
outside the figure!  You example appears to indicate that in the
imshow code I am missing a check somewhere for illegal y values but
getting it right for illegal x values.  My inclination is to disallow
axes borders outside the figure boundary.  Am I correct that you are
only driven to this extreme because you are trying to work around the
preserve bug?  If so, perhaps it will be an acceptable solution to
just fix that bug and raise an exception if someone uses left,bottom<0
or right,top>1.  


JDH