Add create_entity_markers function

[jorgensd]

Convenience function for creating meshtags based of python functions.

Based of what @bleyerj suggested in #26.

I've modified it slightly:

• added some notes on duplicate markers
• added on_boundary option.
• type-hints

Added a demo to highlight how to use it and visualize meshtags with pyvista.

[finsberg]

Thanks this look great! Another option here is to pass the entities as a list of dictionaries so that the user can have entities both with and without on_boundary=True, e.g

entities = [
    {"id": 1, "locator": left, "on_boundary": True},
    {"id": 2, "locator": right, "on_boundary": False},
]

Now, to type this we could use a TypedDict, e.g

import typing

class Tag(typingTypedDict):
    id: int
    locator: typing.Callable[[npt.NDArray[np.floating]], npt.NDArray[np.bool_]]
    on_bounary: bool


entities: list[Tag]

BTW, I solved this using a NamedTuple in fenicsx-pulse, see https://github.com/finsberg/fenicsx-pulse/blob/6c5b8fa4c05352589c7158ec13f6c844aa162abc/src/fenicsx_pulse/geometry.py#L32, but I think a dictionary is probably better since you don't need to import any extra stuff.

[jorgensd]

Thanks this look great! Another option here is to pass the entities as a list of dictionaries so that the user can have entities both with and without on_boundary=True, e.g

entities = [
    {"id": 1, "locator": left, "on_boundary": True},
    {"id": 2, "locator": right, "on_boundary": False},
]

Now, to type this we could use a TypedDict, e.g

import typing

class Tag(typingTypedDict):
    id: int
    locator: typing.Callable[[npt.NDArray[np.floating]], npt.NDArray[np.bool_]]
    on_bounary: bool


entities: list[Tag]

BTW, I solved this using a NamedTuple in fenicsx-pulse, see https://github.com/finsberg/fenicsx-pulse/blob/6c5b8fa4c05352589c7158ec13f6c844aa162abc/src/fenicsx_pulse/geometry.py#L32, but I think a dictionary is probably better since you don't need to import any extra stuff.

I am fine with that as long as we keep the complexity of the input arguments relatively low.

Do you want to make these adaptations and make a test?
@bleyerj what do you think?

[finsberg]

Instead of using dictionaries we have now using tuples instead, where the elements are (tag, locator, on_boundary), with on_boundary being optional.