DimensionGroup¶

class lsst.daf.butler.DimensionGroup(universe: DimensionUniverse, names: Iterable[str] | DimensionGroup = frozenset({}), _conform: bool = True)¶

Bases: object

An immutable, dependency-complete collection of dimensions.

DimensionGroup behaves in many respects like a set of str dimension names that maintains several special subsets and supersets of related dimension elements. It does not fully implement the collections.abc.Set interface, because it defines a few different iteration orders and does not privilege any one of them by implementing __iter__.

Parameters:

universeDimensionUniverse: Object that manages all known dimensions.
namesiterable of str, optional: An iterable of the names of dimensions that must be included in the group. All (recursive) dependencies of these dimensions will also be included. At most one of dimensions and names must be provided.
_conformbool, optional: If True (default), expand to include dependencies. False should only be used for callers that can guarantee that other arguments are already correctly expanded, and is for internal use only.

Notes

DimensionGroup should be used instead of other collections in most contexts where a collection of dimensions is required and a DimensionUniverse is available. Exceptions include cases where order matters (and is different from the consistent ordering defined by the DimensionUniverse), or complete Set semantics are required.

This class is not a Pydantic model, but it implements the __get_pydantic_core_schema__ special method and hence can be used as a field in Pydantic models or [de]serialized directly via pydantic.TypeAdapter, but validation requires a DimensionUniverse to be passed as the “universe” key in the Pydantic validation context. The pydantic_utils.DeferredValidation class can be used to defer validation of this object or other types that use it until that context is available.

Attributes Summary

`data_coordinate_keys`	A set of dimensions ordered like `DataCoordinate.mapping`.
`lookup_order`	A tuple of all elements in the order needed to find their records.
`region_dimension`	Return the most appropriate spatial dimension to use when looking up a region.
`spatial`	Families represented by the spatial elements in this graph.
`temporal`	Families represented by the temporal elements in this graph.
`timespan_dimension`	Return the most appropriate temporal dimension to use when looking up a time span.

Methods Summary

`as_group`()	Return `self`.
`from_simple`(data, universe)	Create an instance of this class from serialized data.
`intersection`(*others)	Construct a new group with only dimensions in all of the operands.
`isdisjoint`(other)	Test whether the intersection of two groups is empty.
`issubset`(other)	Test whether all dimensions in `self` are also in `other`.
`issuperset`(other)	Test whether all dimensions in `other` are also in `self`.
`to_simple`()	Convert this class to a simple data format suitable for serialization.
`union`(*others)	Construct a new group with all dimensions in any of the operands.

Attributes Documentation

data_coordinate_keys¶

A set of dimensions ordered like DataCoordinate.mapping.

This order is defined as all required dimensions followed by all implied dimensions.

lookup_order¶

A tuple of all elements in the order needed to find their records.

Unlike the table definition/topological order (which is what DimensionUniverse.sorted gives you), when dimension A implies dimension B, dimension A appears first.

region_dimension¶

Return the most appropriate spatial dimension to use when looking up a region.

Returns None if there are no appropriate dimensions or more than one spatial family.

spatial¶: Families represented by the spatial elements in this graph.

temporal¶: Families represented by the temporal elements in this graph.

timespan_dimension¶

Return the most appropriate temporal dimension to use when looking up a time span.

Returns None if there are no appropriate dimensions or more than one temporal family.

Methods Documentation

as_group() → DimensionGroup¶

Return self.

Returns:

groupDimensionGroup: Returns itself.

Notes

This is a backwards-compatibility API that allowed both the old DimensionGraph class and DimensionGroup to be coerced to the latter.

Deprecated since version v28: Deprecated as no longer necessary (this method always returns ‘self’). Will be removed after v28.

classmethod from_simple(data: SerializedDimensionGroup, universe: DimensionUniverse) → DimensionGroup¶

Create an instance of this class from serialized data.

Parameters:

dataSerializedDimensionGroup: Serialized data from a previous call to to_simple.
universeDimensionUniverse: Dimension universe in which this dimension group will be defined.

intersection(*others: DimensionGroup) → DimensionGroup¶

Construct a new group with only dimensions in all of the operands.

Parameters:

*othersDimensionGroup: Other groups to compare with.

Returns:

interDimensionGroup: Intersection of all the groups.

Notes

Navigation

DimensionGroup¶