Function decode_cf_variables

xarray/conventions.py:350–495

Decode several CF encoded variables. See: decode_cf_variable

(
    variables: T_Variables,
    attributes: T_Attrs,
    concat_characters: bool | Mapping[str, bool] = True,
    mask_and_scale: bool | Mapping[str, bool] = True,
    decode_times: bool | CFDatetimeCoder | Mapping[str, bool | CFDatetimeCoder] = True,
    decode_coords: bool | Literal["coordinates", "all"] = True,
    drop_variables: T_DropVariables = None,
    use_cftime: bool | Mapping[str, bool] | None = None,
    decode_timedelta: bool
    | CFTimedeltaCoder
    | Mapping[str, bool | CFTimedeltaCoder]
    | None = None,
)

def decode_cf_variables(
    variables: T_Variables,
    attributes: T_Attrs,
    concat_characters: bool | Mapping[str, bool] = True,
    mask_and_scale: bool | Mapping[str, bool] = True,
    decode_times: bool | CFDatetimeCoder | Mapping[str, bool | CFDatetimeCoder] = True,
    decode_coords: bool | Literal["coordinates", "all"] = True,
    drop_variables: T_DropVariables = None,
    use_cftime: bool | Mapping[str, bool] | None = None,
    decode_timedelta: bool
    | CFTimedeltaCoder
    | Mapping[str, bool | CFTimedeltaCoder]
    | None = None,
) -> tuple[T_Variables, T_Attrs, set[Hashable]]:
    """
    Decode several CF encoded variables.

    See: decode_cf_variable
    """
    # Only emit one instance of the decode_timedelta default change
    # FutureWarning. This can be removed once this change is made.
    warnings.filterwarnings("once", "decode_timedelta", FutureWarning)

    dimensions_used_by = defaultdict(list)
    for v in variables.values():
        for d in v.dims:
            dimensions_used_by[d].append(v)

    def stackable(dim: Hashable) -> bool:
        # figure out if a dimension can be concatenated over
        if dim in variables:
            return False
        for v in dimensions_used_by[dim]:
            if v.dtype.kind != "S" or dim != v.dims[-1]:
                return False
        return True

    coord_names = set()

    if isinstance(drop_variables, str):
        drop_variables = [drop_variables]
    elif drop_variables is None:
        drop_variables = []
    drop_variables = set(drop_variables)

    # Time bounds coordinates might miss the decoding attributes
    if decode_times:
        _update_bounds_attributes(variables)

    new_vars = {}
    for k, v in variables.items():
        if k in drop_variables:
            continue
        stack_char_dim = (
            _item_or_default(concat_characters, k, True)
            and v.dtype == "S1"
            and v.ndim > 0
            and stackable(v.dims[-1])