DimensionCombination¶
-
class
lsst.daf.butler.
DimensionCombination
¶ Bases:
lsst.daf.butler.DimensionElement
A
DimensionElement
that provides extra metadata and/or relationship endpoint information for a combination of dimensions.Attributes Summary
RecordClass
The DimensionRecord
subclass used to hold records for this element (type
).alwaysJoin
If True
, always include this element in any query or data ID in which itsrequired
dimensions appear, because it defines a relationship between those dimensions that must always be satisfied.dimensions
The union of required
andimplied
, with all elements inrequired
before any elements inimplied
.governor
The GovernorDimension
that is a required dependency of this element, orNone
if there is no such dimension (GovernorDimension
orNone
).graph
Minimal graph that includes this element ( DimensionGraph
).implied
Other dimensions that are uniquely identified directly by a record of this dimension element. metadata
Additional metadata fields included in this element’s table ( NamedValueSet
ofFieldSpec
).name
Unique string identifier for this endpoint ( str
).required
Dimensions that are necessary to uniquely identify a record of this dimension element. spatial
This endpoint’s SPATIAL
family.temporal
This endpoint’s TEMPORAL
family.topology
The relationship families to which this endpoint belongs, keyed by the category for that family. viewOf
Name of another table this element’s records are drawn from ( str
orNone
).Methods Summary
hasTable
()Return True
if this element is associated with a table (even if that table “belongs” to another element).Attributes Documentation
-
RecordClass
¶ The
DimensionRecord
subclass used to hold records for this element (type
).Because
DimensionRecord
subclasses are generated dynamically, this type cannot be imported directly and hence can only be obtained from this attribute.
-
alwaysJoin
¶ If
True
, always include this element in any query or data ID in which itsrequired
dimensions appear, because it defines a relationship between those dimensions that must always be satisfied.
-
dimensions
¶ The union of
required
andimplied
, with all elements inrequired
before any elements inimplied
.This differs from
self.graph.dimensions
both in order and in content:- as in
self.implied
, implied dimensions are not expanded recursively here; - implied dimensions appear after required dimensions here, instead of being topologically ordered.
As a result, this set is ordered consistently with
self.RecordClass.fields
.- as in
-
governor
¶ The
GovernorDimension
that is a required dependency of this element, orNone
if there is no such dimension (GovernorDimension
orNone
).
-
graph
¶ Minimal graph that includes this element (
DimensionGraph
).self.graph.required
includes all dimensions whose primary key values are sufficient (often necessary) to uniquely identifyself
(includingself
ifisinstance(self, Dimension)
.self.graph.implied
includes all dimensions also identified (possibly recursively) by this set.
-
implied
¶ Other dimensions that are uniquely identified directly by a record of this dimension element.
For elements with a database representation, these are exactly the dimensions used to form foreign key constraints whose fields are not (wholly) also part of the primary key.
Unlike
self.graph.implied
, this set is not expanded recursively.
-
metadata
¶ Additional metadata fields included in this element’s table (
NamedValueSet
ofFieldSpec
).
-
required
¶ Dimensions that are necessary to uniquely identify a record of this dimension element.
For elements with a database representation, these dimension are exactly those used to form the (possibly compound) primary key, and all dimensions here that are not
self
are also used to form foreign keys.For
Dimension
instances, this should be exactly the same asgraph.required
, but that may not be true forDimensionElement
instances in general. When they differ, there are multiple combinations of dimensions that uniquely identify this element, but this one is more direct.
-
topology
¶ The relationship families to which this endpoint belongs, keyed by the category for that family.
Methods Documentation
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