Support individual styling of major and minor grid through rcParams #29481

konmenel · 2025-01-18T20:38:12Z

PR summary

Possibly closes #13919 issue. Additionally, PR #26121 also tried to solve the same issue but I understand that it is not backwards compatible and there haven't been any updates since 2023. My implementation should be backwards compatible.

I have tested the code with pytest. Some tests failed on my machine, but all were latex tests. The problem is probably my latex installation.

I also tested to code with a small python script that:

Modifies the rcParams at runtime for 3 different scenarios and uses
Uses mstyle files for the same 3 scenario

The results were identical and as expected.

Test

My test script:

# test_grid_rcparams.py
import matplotlib as mpl
import matplotlib.pyplot as plt

dpi = 150
#---------------------------------------------
# RUNTIME
#---------------------------------------------
mpl.rcdefaults()
mpl.rcParams["axes.grid"] = True
mpl.rcParams["ytick.minor.visible"] = True
mpl.rcParams["xtick.minor.visible"] = True
mpl.rcParams["axes.grid.which"] = "both"
mpl.rcParams["grid.color"] = "red"
mpl.rcParams["grid.linewidth"] = 1
mpl.rcParams["grid.linestyle"] = "-"
mpl.rcParams["grid.alpha"] = 1
plt.figure()
plt.plot([0, 1], [0, 1])
plt.gcf().savefig("runtime1.png", dpi=dpi)

mpl.rcdefaults()
mpl.rcParams["axes.grid"] = True
mpl.rcParams["ytick.minor.visible"] = True
mpl.rcParams["xtick.minor.visible"] = True
mpl.rcParams["axes.grid.which"] = "both"
mpl.rcParams["grid.color"] = "red"
mpl.rcParams["grid.linewidth"] = 1
mpl.rcParams["grid.linestyle"] = "-"
mpl.rcParams["grid.alpha"] = 1

mpl.rcParams["grid.major.color"] = "black"
mpl.rcParams["grid.major.linewidth"] = 2
mpl.rcParams["grid.major.linestyle"] = ":"
plt.figure()
plt.plot([0, 1], [0, 1])
plt.gcf().savefig("runtime2.png", dpi=dpi)

mpl.rcdefaults()
mpl.rcParams["axes.grid"] = True
mpl.rcParams["ytick.minor.visible"] = True
mpl.rcParams["xtick.minor.visible"] = True
mpl.rcParams["axes.grid.which"] = "both"
mpl.rcParams["grid.color"] = "red"
mpl.rcParams["grid.linewidth"] = 1
mpl.rcParams["grid.linestyle"] = "-"
mpl.rcParams["grid.alpha"] = 1

mpl.rcParams["grid.minor.color"] = "red"
mpl.rcParams["grid.minor.linewidth"] = 0.5
mpl.rcParams["grid.minor.linestyle"] = ":"
mpl.rcParams["grid.minor.alpha"] = 0.5
plt.figure()
plt.plot([0, 1], [0, 1])
plt.gcf().savefig("runtime3.png", dpi=dpi)


#---------------------------------------------
# MSTYLE FILE
#---------------------------------------------
mpl.rcdefaults()
plt.style.use("./style1.mstyle")
plt.figure()
plt.plot([0, 1], [0, 1])
plt.gcf().savefig("mstyle1.png", dpi=dpi)

mpl.rcdefaults()
plt.style.use("./style2.mstyle")
plt.figure()
plt.plot([0, 1], [0, 1])
plt.gcf().savefig("mstyle2.png", dpi=dpi)

mpl.rcdefaults()
plt.style.use("./style3.mstyle")
plt.figure()
plt.plot([0, 1], [0, 1])
plt.gcf().savefig("mstyle3.png", dpi=dpi)

# style1.mstyle
axes.grid: True
ytick.minor.visible: True
xtick.minor.visible: True
axes.grid.which: both
grid.color: red
grid.linewidth: 1
grid.linestyle: -
grid.alpha: 1

# style2.mstyle
axes.grid: True
ytick.minor.visible: True
xtick.minor.visible: True
axes.grid.which: both
grid.color: red
grid.linewidth: 1
grid.linestyle: -
grid.alpha: 1

grid.major.color: black
grid.major.linewidth: 2
grid.major.linestyle: :

# style3.mstyle
axes.grid: True
ytick.minor.visible: True
xtick.minor.visible: True
axes.grid.which: both
grid.color: red
grid.linewidth: 1
grid.linestyle: -
grid.alpha: 1

grid.minor.color: red
grid.minor.linewidth: 0.5
grid.minor.linestyle: :
grid.minor.alpha: 0.5

Results

PR checklist

"closes Impossible to configure minor/major grid line style independently in rcParams #13919" is in the body of the PR description to link the related issue
new and changed code is tested
Plotting related features are demonstrated in an example
New Features and API Changes are noted with a directive and release note
Documentation complies with general and docstring guidelines

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timhoffm

Thanks for the PR. The solution is surprisingly simple. I would have thought that there are more complications because of the concurrent settings and the need for backward compatibility.

The only improvement needed is the clearer distinction on the color and linewidth parameter values between "none" and None.

lib/matplotlib/rcsetup.py

lib/matplotlib/axis.py

timhoffm · 2025-01-27T14:58:27Z

One related aspect to think about: Do we anticipate that we'll need a distinction between x and y axis as well? Because if so, we should directly introduce these.

The `*_or_None` validators have accepted any capitalization of the string "none" as input. This is overly permissive and will likely lead to conflicts in the future because we cannot distinguish between resolving to `None` and `"none"` which may be need for some parameters in the future. Inspired by matplotlib#29481.

konmenel · 2025-01-27T15:19:24Z

I made the suggested changes.

One related aspect to think about: Do we anticipate that we'll need a distinction between x and y axis as well? Because if so, we should directly introduce these.

Can you clarify what you meant by "a distinction between x and y axis"? Do you mean something like

rcParams["grid.major.xaxis.linestyle"] = ":"
rcParams["grid.major.yaxis.linestyle"] = "-"

The `*_or_None` validators have accepted any capitalization of the string "none" as input. This is overly permissive and will likely lead to conflicts in the future because we cannot distinguish between resolving to `None` and `"none"` which may be need for some parameters in the future. Inspired by matplotlib#29481.

konmenel · 2025-01-27T15:29:36Z

Sorry I forgot to update the ".pyi" file

timhoffm · 2025-01-27T16:22:29Z

between x and y axis"? Do you mean something like
rcParams["grid.major.xaxis.linestyle"] = ":"
rcParams["grid.major.yaxis.linestyle"] = "-"

Basically yes. Exact spelling t.b.d.

lib/matplotlib/rcsetup.pyi

konmenel · 2025-01-27T18:54:20Z

Basically yes. Exact spelling t.b.d.

I think this is possible however it might look "ugly". The change will require the Tick class to know which child (XTick, YTick) was instantiated since the lines are created in the parent class.

One possible way is by accessing the self.__name__ attribute which should either be "xtick" or "ytick" since the base class is never instantiated. However, this might cause problems if this attribute ever changes which might be hard to debug. It is also possible to add a new attribute to the Tick class which will default to None and will be set by the child class to be used explicitly for this purpose so that we don't use the __name__ attribute.

Another way is to add an extra required argument to the constructor of Tick, probably an enum or a bool. For instance, an argument axis that will be either 1 or 2 if XTick or YTick has called the Tick.__init__ method, respectively.

Any thoughts on those?

timhoffm · 2025-01-27T21:02:27Z

We already rely on Tick.__name__ see

matplotlib/lib/matplotlib/axis.py

Lines 106 to 116 in 3b329d9

    
           name = self.__name__ 
        
           major_minor = "major" if major else "minor" 
        
           self._size = mpl._val_or_rc(size, f"{name}.{major_minor}.size") 
        
           self._width = mpl._val_or_rc(width, f"{name}.{major_minor}.width") 
        
           self._base_pad = mpl._val_or_rc(pad, f"{name}.{major_minor}.pad") 
        
           color = mpl._val_or_rc(color, f"{name}.color") 
        
           labelcolor = mpl._val_or_rc(labelcolor, f"{name}.labelcolor") 
        
           if cbook._str_equal(labelcolor, 'inherit'): 
        
               # inherit from tick color 
        
               labelcolor = mpl.rcParams[f"{name}.color"] 
        
           labelsize = mpl._val_or_rc(labelsize, f"{name}.labelsize")

It's ok to use that.

Spelling: We have "xaxis", "xticks", "xscale" as axis-dependent names (but they are all also used in the python interface). We do not have any xgrid or similar names. Options:

"xgrid.major.linestyle" - in analogy to "xticks"
"grid.xaxis.major.linestyle" / "grid.x.major.linestyle" - still put it under the "grid" top level group
"xtick.major.grid.linestyle" - put everything under the corresponding tick
"xaxis.grid.major.linestyle" - put everything under the corresponding axis

None of them look like the obvious right choice to me.

konmenel · 2025-01-27T23:16:51Z

Out of the four, I prefer two:

"xtick.major.grid.linestyle" - many options already exist under "xtick.major.*" so it is logical.
"grid.xaxis.major.linestyle" - configures similar to both axis. Also, it will be in a similar place in the matplotlibrc making easier to find if you are looking for it.

I will try to implement the second one for now. I can change the key later.

The `*_or_None` validators have accepted any capitalization of the string "none" as input. This is overly permissive and will likely lead to conflicts in the future because we cannot distinguish between resolving to `None` and `"none"` which may be need for some parameters in the future. Inspired by matplotlib#29481.

konmenel · 2025-01-28T00:36:00Z

I implemented the x and y axis distinction however I came across something that needs further clarification. Right now "grid.xaxis.major.linestyle" is a valid key but "grid.xaxis.linestyle" is not. Should it be a valid option as well? If so it is unclear which of "grid.major.linestyle"and "grid.xaxis.linestyle" should take precedence.

timhoffm · 2025-01-28T08:18:35Z

No, we don't need "grid.xaxis.linestyle". If starting from scratch, I'd just have the granular settings "grid.xaxis.major.linestyle" etc. After all, these are advanced style configuration options, and if somebody cares to adapt them, it's ok to write out the details. We keep the high-level ones "grid.linestyle" for backward compatibility (and it is a nice convenience) but we don't need the middle-ground.

timhoffm

Looks good. Please add a What's New note according to https://matplotlib.org/devdocs/devel/api_changes.html#what-s-new-notes

lib/matplotlib/axis.py

`_val_or_rc` now accept multiple rc names and return val or the first non-None value in rcParams. Returns last rc name if all other are None. Also, simplified code in `Tick` for grid lines creatation

konmenel · 2025-01-29T11:28:30Z

Do you want me to create the test in the file "test_rcparams.py" or create a separate file?

timhoffm · 2025-01-29T12:00:58Z

Please put it in test_axis.py. This is where the semantic code lives and where it logically belongs. test_rcparams.py is only for the rcparams infrastructure not testind individual values.

konmenel · 2025-01-29T16:46:42Z

I was working on the test and I realised that the get_gridlines() only returns the major gridlines. If it's okay I will introduce two new functions get_major_gridlines() and get_minor_gridlines() to be explicit. That way I will able to easily extract the minor gridlines as well. Also, the original function will now call the get_major_gridlines() to be backwards compatible

timhoffm · 2025-01-29T17:02:01Z

Then use ax.xaxis.get_major_ticks()[0].gridline. There are various ways to drill down, and not all are complete or consistent. Sorting/consolidating that is for another time. Let's not create more functions as part of this PR.

doc/users/next_whats_new/new_rcparams_grid_options.rst

konmenel · 2025-01-29T22:46:14Z

I fix the spelling so all tests should pass now. If there is anything else please let me know.

carlosgmartin · 2025-03-31T19:47:33Z

@timhoffm Any idea when this might be merged?

timhoffm · 2025-04-01T00:38:30Z

This needs a second review by a core developer, and review time is scarce. However, this is flagged for 3.11 and I'm pretty sure it will get the attention in time for the next release.

doc/users/next_whats_new/new_rcparams_grid_options.rst

lib/matplotlib/axis.py

lib/matplotlib/rcsetup.py

lib/matplotlib/rcsetup.pyi

Removed outer brackets

konmenel · 2025-06-10T14:06:00Z

@QuLogic I have made the changes you suggested. If there is anything more I need to do, please let me know.

QuLogic · 2025-06-11T04:07:44Z

stubtest is still complaining about _validate_linestyle since you seemed to have changed only one file.

konmenel · 2025-06-11T11:12:39Z

Yes, I did it that way because this is how it is in the main branch. I never modified the function _validate_linestyle in the PR, I just removed it from ci/mypy-stubtest-allowlist.txt.

Do you want me to modify the function or revert the change in "ci/mypy-stubtest-allowlist.txt"?

konmenel added 2 commits January 17, 2025 17:39

Possible fix for issue matplotlib#13919

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fix flake warnings

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github-actions bot added topic: rcparams topic: ticks axis labels labels Jan 18, 2025

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timhoffm changed the title ~~FIX: issue #13919~~ Support individual styling of major and minor grid through rcParams Jan 27, 2025

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Resolve suggested changes

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timhoffm mentioned this pull request Jan 27, 2025

MNT: Deprecate other capitalization than "None" in matplotlibrc #29529

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Add new validators in stub file

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make stub file arguments same as runtime

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konmenel added 2 commits January 28, 2025 00:21

Add distinction for x and y axis in grid line options

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fix flake8

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konmenel added 3 commits January 28, 2025 13:45

Add What's New note

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Extend _val_or_rc to support multiply names

39eef79

`_val_or_rc` now accept multiple rc names and return val or the first non-None value in rcParams. Returns last rc name if all other are None. Also, simplified code in `Tick` for grid lines creatation

Fix linting for and _validate_linestyle_or_None to mypy allowlist

a4e6f44

Update What's New note and reduced example

cd3c260

Add testing for grid.major/minor.* in rcParams

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konmenel added 3 commits January 29, 2025 22:33

fix indentation and linting

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Fix example description

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Fix spelling

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Merge branch 'main' into fix-issue-13919

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timhoffm approved these changes Feb 1, 2025

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timhoffm mentioned this pull request Feb 2, 2025

[ENH]: Allow rcParams to inherit from other rcParams #25641

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timhoffm mentioned this pull request Feb 10, 2025

[ENH]: Add Independent xlabelpad and ylabelpad Options to rcParams #28860

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konmenel added 5 commits June 9, 2025 13:55

Fix type

830b8a0

Fix formatting

5b623a3

Removed outer brackets

validate_color_or_None private and fix argument names

6db787a

Fix validator name in stub file as well

a6db063

correct validators for grid.*.color keys

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Support individual styling of major and minor grid through rcParams #29481

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Support individual styling of major and minor grid through rcParams #29481

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konmenel commented Jan 18, 2025

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