to_xarray: auto-convert units

Closes #85 (closed)

data.tools:

• auto-convert units in to_xarray
• Info: always have units in meta (this causes a lot of trouble, should be done in a separate merge request)
• added convenience routines for unit comparison (compatible_units, equivalent_units)

requested review from @mlange

assigned to @muellese

Regarding test errors... Example code from test_parametric.py:

        time = datetime(2000, 1, 1)
        in_info = fm.Info(
            time=None,
            grid=fm.UniformGrid((20,)),
            units="m",
        )

        source = fm.modules.ParametricGrid(
            info=in_info,
            func=lambda t, x: x,
        )
        trigger = fm.modules.TimeTrigger(
            in_info=fm.Info(time=None, grid=None, units=None),
            start=time,
            step=timedelta(days=1),
        )
        sink = fm.modules.DebugConsumer(
            {"Input": fm.Info(None, grid=None)},
            start=datetime(2000, 1, 1),
            step=timedelta(days=1),
        )

        composition = fm.Composition([source, trigger, sink])
        composition.initialize()

        source.outputs["Grid"] >> trigger.inputs["In"]
        trigger.outputs["Out"] >> sink.inputs["Input"]

Here, trigger just passes on the data, in meters.
sink specifies no units, so with the new units handling, it expects dimensionless. This does not work, and also should not.

It worked before, because units was not in the info and thus ignored. Which was a bug.

OK. This sounds hard. I would skip this refactoring at least for this merge request.

I can do the test fixes in an MR on top of this.

(would do the rebase first)

(and drop the last, reverting commit...)

added 1 commit

• f10c1e19 - Info: remove default units again

Compare with previous version

changed the description

mentioned in merge request !215 (merged)

This is contained in !215 (merged), minus revert, plus test fixes.

closed