import earthkit.plots modifies plt rcParams

[Oisin-M]

What happened?

Not sure if this is intended or unintended, so I am opening an issue to discuss @JamesVarndell . This is related to ecmwf/earthkit#116. We have the behaviour that when one does import earthkit.plots, it modifies matplotlib's style.

From what I see, the specific offending import is

from earthkit.plots.schemas import schema

which updates plt rcParams

What are the steps to reproduce the bug?

Version

0.3.2

Platform (OS and architecture)

Relevant log output

Accompanying data

No response

Organisation

No response

[JamesVarndell]

Thanks @Oisin-M.

As you correctly pointed out, when earthkit-plots is imported, the schema submodule modifies matplotlib’s rcParams to set global plotting style defaults. This approach lets us enforce consistent layouts and styles across all earthkit-plots charts.

However, as seen in ecmwf/earthkit#116, this can be a significant problem if users import earthkit-plots without realising, since it changes the global matplotlib settings without their knowledge. The lazy import fix should help by only modifying rcParams when earthkit-plots is explicitly imported, making this behavior more predictable.

Ideally though, we should only apply earthkit-plots styles to plots created by earthkit-plots, rather than changing global settings. I plan to investigate this further - matplotlib’s rc_context context manager looks promising for this purpose.

[Oisin-M]

That rc_context approach looks very promising for this case @JamesVarndell! Another idea could be if the updating of rcparams is heavy, might be good to apply the rcparams updates only when .plot() is called to reduce the upfront ekp import time (I haven't profiled so this could be a useless suggestion).

I'll close ecmwf/earthkit#116 in favour of this issue.