Function process_subset_opt

xarray/structure/concat.py:419–550

(
        opt: ConcatOptions | Iterable[Hashable] | CombineKwargDefault,
        subset: Literal["coords", "data_vars"],
    )

        concat_dim_lengths.append(ds.sizes.get(dim, 1))

    def process_subset_opt(
        opt: ConcatOptions | Iterable[Hashable] | CombineKwargDefault,
        subset: Literal["coords", "data_vars"],
    ) -> None:
        original = set(concat_over)
        compat_str = (
            compat._value if isinstance(compat, CombineKwargDefault) else compat
        )
        assert compat_str is not None
        if isinstance(opt, str | CombineKwargDefault):
            if opt == "different":
                if isinstance(compat, CombineKwargDefault) and compat != "override":
                    if not isinstance(opt, CombineKwargDefault):
                        emit_user_level_warning(
                            compat.warning_message(
                                "This change will result in the following ValueError: "
                                f"Cannot specify both {subset}='different' and compat='override'.",
                                recommend_set_options=False,
                            ),
                            FutureWarning,
                        )

                if compat == "override":
                    raise ValueError(
                        f"Cannot specify both {subset}='different' and compat='override'."
                        + (
                            compat.error_message()
                            if isinstance(compat, CombineKwargDefault)
                            else ""
                        )
                    )
                # all nonindexes that are not the same in each dataset
                for k in getattr(datasets[0], subset):
                    if k not in concat_over:
                        equal = None

                        variables = [
                            ds.variables[k] for ds in datasets if k in ds.variables
                        ]

                        if len(variables) == 1:
                            # coords="different" doesn't make sense when only one object
                            # contains a particular variable.
                            break
                        elif len(variables) != len(datasets) and opt == "different":
                            raise ValueError(
                                f"{k!r} not present in all datasets and coords='different'. "
                                f"Either add {k!r} to datasets where it is missing or "
                                "specify coords='minimal'."
                            )

                        # first check without comparing values i.e. no computes
                        for var in variables[1:]:
                            equal = getattr(variables[0], compat_str)(
                                var, equiv=lazy_array_equiv
                            )
                            if equal is not True:
                                # exit early if we know these are not equal or that