plotting from ipython

[kakila]

Hi,
Thanks for the nice tool.
I have tried to search the documentation for the way to plot form within ipython.
Is this possible? I tried several backends but none is creating a window.

Thanks

[marcomusy]

Hi, sorry for the late reply, have you tried:

settings.default_backend = "vtk" 

[paulbrodersen]

Hi, great library but I just ran into the same issue. While setting the default backend to VTK solves the problem, is there an explanation why vedo defaults to "2d" in an ipython REPL?

vedo --info
# vedo version      : 2024.5.1  (https://vedo.embl.es)             
# vtk version       : 9.3.0
# numpy version     : 1.23.5
# python version    : 3.10.14 | packaged by conda-forge | (main, Mar 20 2024, 12:45:18) [GCC 12.3.0]
# python interpreter: /home/paul/src/miniconda3/envs/brainrender_dev/bin/python3.10
# installation point: /home/paul/src/miniconda3/envs/brainrender_dev/lib/python3.10/site-packages/v
# system            : Linux 5.4.0-148-generic posix x86_64
# k3d version       : 2.16.1

When running from shell:

python -c "import vedo; print(vedo.settings.default_backend)"
# vtk

When running in an IPython REPL:

(brainrender_dev) paul@paul-XPS-15-9560:~/src/BrainRender$ ipython
Python 3.10.14 | packaged by conda-forge | (main, Mar 20 2024, 12:45:18) [GCC 12.3.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.23.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import vedo; print(vedo.settings.default_backend)
2d

Presumably there are good reasons for the switch, but maybe it's worth raising a warning whenever the '2d' backend is selected automatically? It took a hot minute to narrow the issue down to a ipython-vedo interaction.

[marcomusy]

Hi - yes indeed there is a "good" reason ... the visualization part is normally delegated to an opengl graphic rendering which pops up in a separate window.
In ipyhton envs this is not what normally one would expect hence the change in the behavior.
I will add this explanation in the docs to clarify it, thanks for drawing my attention to it!

[paulbrodersen]

Hi, I think there is some confusion here with Jupyter notebooks (which used to be called IPython notebooks).
I am talking about the IPython REPL, a replacement for the standard python console. The ipython REPL is a terminal program, so figures (matplotlib, cairo, etc) are spawned as their own processes in their own windows.

[marcomusy]

Oh OK sorry!
We do this in vedo/settings.py in Settings.__init__():

        self.default_backend = "vtk"
        try:
            get_ipython()
            self.default_backend = "2d"
        except NameError:
            pass

is there a way to distinguish or separate the case of a REPL vs jupyter env?

[paulbrodersen]

A couple of solutions have been discussed on Stackoverflow.

The first answer looks reasonably robust and works on my machine:

def is_notebook() -> bool:
    try:
        shell = get_ipython().__class__.__name__
        if shell == 'ZMQInteractiveShell':
            return True   # Jupyter notebook or qtconsole
        elif shell == 'TerminalInteractiveShell':
            return False  # Terminal running IPython
        else:
            return False  # Other type (?)
    except NameError:
        return False      # Probably standard Python interpreter

So the snippet above would be:

if is_notebook():
    self.default_backend = "2d"
else:
    self.default_backend = "vtk"

[paulbrodersen]

Also note the comment below that answer on detecting google colab notebooks:

get_ipython().__class__.__module__ == "google.colab._shell"

Though is suspect that vedo is probably incompatible with colab anyway due to the lack of display parameters?

[marcomusy]

Thanks a lot Paul! This is very useful!

suspect that vedo is probably incompatible with colab anyway due to the lack of display parameters

in fact you can run vedo in a colab env using this.