IPython console Matplotlib rc parameters are inconsistent when switching backends

[mrclary]

Problem Description

Spyder's IPython Console does not behave consistently with respect to Matplotlib rc settings when switching backends. The following table summarizes the problem.

Backend Preference	Toggle Backend	Expected Params	Actual Params
Inline	initial	Spyder inline preferences	Spyder inline preferences
Inline	to interactive	matplotlibrc	Spyder kernel default
Inline	back to inline	Spyder inline preferences	Spyder kernel default
Interactive	initial	matplotlibrc	Spyder inline preferences
Interactive	to inline	Spyder inline preferences	Spyder kernel default
Interactive	back to interactive	matplotlibrc	Spyder inline preferences

With inline graphics backend:

In [1]: import matplotlib as mpl

In [2]: mpl.rcParams['savefig.format'], mpl.rcParams['figure.dpi'], mpl.rcParams['figure.figsize'], mpl.rcParams['font.size'], mpl.rcParams['figure.subplot.bottom']
Out[2]: ('pdf', 144.0, [6.0, 4.0], 8.0, 0.05)

In [3]: %matplotlib auto
Using matplotlib backend: QtAgg
Using matplotlib backend: QtAgg

In [4]: mpl.rcParams['savefig.format'], mpl.rcParams['figure.dpi'], mpl.rcParams['figure.figsize'], mpl.rcParams['font.size'], mpl.rcParams['figure.subplot.bottom']
Out[4]: ('pdf', 72.0, [6.0, 4.0], 10.0, 0.125)

In [5]: %matplotlib inline

In [6]: mpl.rcParams['savefig.format'], mpl.rcParams['figure.dpi'], mpl.rcParams['figure.figsize'], mpl.rcParams['font.size'], mpl.rcParams['figure.subplot.bottom']
Out[6]: ('pdf', 72.0, [6.0, 4.0], 10.0, 0.125)

In [7]: mpl.rc_file_defaults()

In [8]: mpl.rcParams['savefig.format'], mpl.rcParams['figure.dpi'], mpl.rcParams['figure.figsize'], mpl.rcParams['font.size'], mpl.rcParams['figure.subplot.bottom']
Out[8]: ('pdf', 99.0, [7.0, 5.0], 9.0, 0.1)

As shown, after switching to Qt backend, the parameters are updated to the kernel defaults (https://github.com/spyder-ide/spyder-kernels/blob/09c370aab411c954f869649279481636f666098b/spyder_kernels/console/start.py#L101C1-L116C1). Except that the savefig.format

Versions

• Spyder version: 6.0.0a5 (standalone)
• Python version: 3.10.13 64-bit
• Qt version: 5.15.8
• PyQt5 version: 5.15.9
• Operating System: macOS-14.4.1-x86_64-i386-64bit

Dependencies

# Mandatory:
atomicwrites >=1.2.0              :  1.4.1 (OK)
chardet >=2.0.0                   :  5.2.0 (OK)
cloudpickle >=0.5.0               :  3.0.0 (OK)
cookiecutter >=1.6.0              :  2.5.0 (OK)
diff_match_patch >=20181111       :  20230430 (OK)
intervaltree >=3.0.2              :  3.1.0 (OK)
IPython >=8.13.0,<9.0.0,!=8.17.1  :  8.21.0 (OK)
jedi >=0.17.2,<0.20.0             :  0.19.1 (OK)
jellyfish >=0.7                   :  1.0.3 (OK)
jsonschema >=3.2.0                :  4.21.1 (OK)
keyring >=17.0.0                  :  24.3.0 (OK)
nbconvert >=4.0                   :  7.16.0 (OK)
numpydoc >=0.6.0                  :  1.6.0 (OK)
parso >=0.7.0,<0.9.0              :  0.8.3 (OK)
pexpect >=4.4.0                   :  4.9.0 (OK)
pickleshare >=0.4                 :  0.7.5 (OK)
psutil >=5.3                      :  5.9.8 (OK)
pygments >=2.0                    :  2.17.2 (OK)
pylint >=3.1,<4                   :  3.1.0 (OK)
pylint_venv >=3.0.2               :  3.0.3 (OK)
pyls_spyder >=0.4.0               :  0.4.0 (OK)
pylsp >=1.11.0,<1.12.0            :  1.11.0 (OK)
pylsp_black >=2.0.0,<3.0.0        :  2.0.0 (OK)
pyuca >=1.2                       :  1.2 (OK)
qdarkstyle >=3.2.0,<3.3.0         :  3.2.3 (OK)
qstylizer >=0.2.2                 :  0.2.2 (OK)
qtawesome >=1.3.1,<1.4.0          :  1.3.1 (OK)
qtconsole >=5.5.1,<5.6.0          :  5.5.1 (OK)
qtpy >=2.4.0                      :  2.4.1 (OK)
rtree >=0.9.7                     :  1.2.0 (OK)
setuptools >=49.6.0               :  69.0.3 (OK)
sphinx >=0.6.6                    :  7.2.6 (OK)
spyder_kernels >=3.0.0b5,<3.0.0b6 :  3.0.0b5 (OK)
superqt >=0.6.1,<1.0.0            :  0.6.1 (OK)
textdistance >=4.2.0              :  4.5.0 (OK)
three_merge >=0.1.1               :  0.1.1 (OK)
watchdog >=0.10.3                 :  4.0.0 (OK)
zmq >=24.0.0                      :  25.1.2 (OK)

# Optional:
cython >=0.21                     :  3.0.8 (OK)
matplotlib >=3.0.0                :  3.8.2 (OK)
numpy >=1.7                       :  1.26.4 (OK)
pandas >=1.1.1                    :  2.2.0 (OK)
scipy >=0.17.0                    :  1.12.0 (OK)
sympy >=0.7.3                     :  1.12 (OK)

[ccordoba12]

Hey @mrclary, thanks for reporting. We don't respect the Matplotlib rc default parameters because we don't read them to set them in the kernel (we use the option set by users in our Preferences dialog).

I guess we'd need to do that to fix this issue, but since it's not critical, I'm going to leave it for 6.1

[mrclary]

There are two prongs to this issue. First, if we only apply the settings conditioned on whether inline is the backend, then these settings will not incorrectly override the user's rc settings on kernel startup. Second, when switching from inline to a different backend in the same kernel, we only have to add matplotlib.rc_file_defaults() to the commands that change the backend.

I'll take a look and propose a fix.

[mrclary]

@impact27, do you have any insight on this?