DimensionCombination¶

class lsst.daf.butler.DimensionCombination¶

Bases: DimensionElement

Element with extra information.

A DimensionElement that provides extra metadata and/or relationship endpoint information for a combination of dimensions.

Attributes Summary

`RecordClass`	Return the record subclass for this element.
`alwaysJoin`	Indicate if the element should always be included.
`dimensions`	Return all dimensions.
`governor`	Return the governor dimension.
`graph`	Return minimal graph that includes this element (`DimensionGraph`).
`implied`	Return the implied dimensions.
`metadata`	Additional metadata fields included in this element's table.
`name`	Return unique string identifier for this endpoint (`str`).
`required`	Return the required dimensions.
`spatial`	Return this endpoint's `SPATIAL` family.
`temporal`	Return this endpoint's `TEMPORAL` family.
`topology`	Return the relationship families to which this endpoint belongs.
`viewOf`	Name of another table this element's records are drawn from.

Methods Summary

`from_json`(json_str[, universe, registry])	Return new class from JSON string.
`from_simple`(simple[, universe, registry])	Construct a new object from the simplified form.
`hasTable`()	Indicate if this element is associated with a table.
`to_json`([minimal])	Convert this class to JSON form.
`to_simple`([minimal])	Convert this class to a simple python type.

Attributes Documentation

RecordClass¶

Return the record subclass for this element.

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¶

Indicate if the element should always be included.

If True, always include this element in any query or data ID in which its required dimensions appear, because it defines a relationship between those dimensions that must always be satisfied.

dimensions¶

Return all dimensions.

The union of required and implied, with all elements in required before any elements in implied.

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.

governor¶

Return the governor dimension.

This is the GovernorDimension that is a required dependency of this element, or None if there is no such dimension (GovernorDimension or None).

graph¶

Return minimal graph that includes this element (DimensionGraph).

self.graph.required includes all dimensions whose primary key values are sufficient (often necessary) to uniquely identify self (including self if isinstance(self, Dimension). self.graph.implied includes all dimensions also identified (possibly recursively) by this set.

implied¶

Return the implied dimensions.

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 of FieldSpec).

name¶: Return unique string identifier for this endpoint (str).

required¶

Return the required dimensions.

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 as graph.required, but that may not be true for DimensionElement instances in general. When they differ, there are multiple combinations of dimensions that uniquely identify this element, but this one is more direct.

spatial¶: Return this endpoint’s SPATIAL family.

temporal¶: Return this endpoint’s TEMPORAL family.

topology¶

Return the relationship families to which this endpoint belongs.

It is keyed by the category for that family.

viewOf¶

Name of another table this element’s records are drawn from.

(str or None).

Methods Documentation

classmethod from_json(json_str: str, universe: DimensionUniverse | None = None, registry: Registry | None = None) → SupportsSimple¶

Return new class from JSON string.

Converts a JSON string created by to_json and return something of the supplied class.

Parameters:

json_strstr: Representation of the dimensions in JSON format as created by to_json().
universeDimensionUniverse, optional: The special graph of all known dimensions. Passed directly to from_simple().
registrylsst.daf.butler.Registry, optional: Registry to use to convert simple name of a DatasetType to a full DatasetType. Passed directly to from_simple().

Returns:

constructedAny: Newly-constructed object.

classmethod from_simple(simple: str, universe: DimensionUniverse | None = None, registry: Registry | None = None) → DimensionElement¶

Construct a new object from the simplified form.

Usually the data is returned from the to_simple method.

Parameters:

simplestr: The value returned by to_simple().
universeDimensionUniverse: The special graph of all known dimensions.
registrylsst.daf.butler.Registry, optional: Registry from which a universe can be extracted. Can be None if universe is provided explicitly.

Returns:

dataIdDimensionElement: Newly-constructed object.

hasTable() → bool¶

Indicate if this element is associated with a table.

Return True if this element is associated with a table (even if that table “belongs” to another element).

to_json(minimal: bool = False) → str¶

Convert this class to JSON form.

The class type is not recorded in the JSON so the JSON decoder must know which class is represented.

Parameters:

minimalbool, optional: Use minimal serialization. Requires Registry to convert back to a full type.

Returns:

jsonstr: The class in JSON string format.

to_simple(minimal: bool = False) → str¶

Convert this class to a simple python type.

This is suitable for serialization.

Parameters:

minimalbool, optional: Use minimal serialization. Has no effect on for this class.

Returns:

simplestr: The object converted to a single string.

Navigation

DimensionCombination¶