Re: [Matplotlib-users] Rotating in imshow

[Eric F. <ef...@ha...>]

Thomas Robitaille wrote:
>>> It looks like rotation/translation should be easy to do with 
>>> Affine2D, so I tried using it, but I can't seem to get it to work as 
>>> expected - here is an example of how I am using it:
>>
>> Based on a quick look at image.py and _image.cpp, it appears that 
>> there is a low-level capability to rotate an image in the latter, but 
>> no support at higher levels.  It also looks to me like adding that 
>> support would not be trivial--doing it right would take more than just 
>> calling the low-level apply_rotation method.  Mike D. would be the 
>> expert on this, though.
> 
> Does this mean that the transform= keyword has no effect on imshow in 
> general?

It does look like it is ignored.  It is a kwarg for Artists that is not 
supported by all.  The fact that one can specify it and get no feedback 
is a bug.


> 
> I attempted to use the pcolormesh() method, which worked, but is 
> impractical, as a 1000x1000 image produces a 300Mb EPS file when plotted 
> in this way.

There is some infrastructure for handling this via selective 
rasterization of artists, but I can never remember exactly what its 
status is; I don't see anything in the examples.  The topic comes up on 
the list at perhaps 6-month intervals.  Personally, I would very much 
like to see the selective rasterization capability fully developed and 
exposed, complete with documentation and examples; it is important for 
exactly the reason you note above.  It is not something I will be able 
to work on myself, unfortunately.

Eric