DataUnit¶

class lsst.daf.butler.DataUnit(name, requiredDependencies, optionalDependencies, link=(), table=None, spatial=False)¶

A discrete abstract unit of data that can be associated with metadata and used to label datasets.

DataUnit instances represent concrete units such as e.g. Camera, Sensor, Visit and SkyMap.

Parameters:

name : str: Name of this DataUnit. Also assumed to be the name of the primary table (if present).
requiredDependencies : frozenset: Related DataUnit instances on which existence this DataUnit instance depends.
optionalDependencies : frozenset: Related DataUnit instances that may also be provided (and when they are, they must be kept in sync).
link : tuple: Names of columns that form the DataUnit specific part of the primary-key in this DataUnit table and are also the names of the link column in the Datasets table.
table : sqlalchemy.core.Table, optional: When not None the primary table entry corresponding to this DataUnit.
spatial : bool, optional: Is this a spatial DataUnit? If so then it either has a region column, or some other way to get a region (e.g. SkyPix).

Attributes Summary

`dependencies`	The union of `requiredDependencies` and `optionalDependencies` (`frozenset`, read-only).
`link`	Names of columns that form the `DataUnit` specific part of the primary-key in this `DataUnit` table and are also the names of the link column in the Datasets table (`tuple`).
`linkColumns`	Dictionary keyed on `link` names with `sqlalchemy.Column` entries into this `DataUnit` primary table as values (`dict`).
`name`	Name of this `DataUnit` (`str`, read-only).
`optionalDependencies`	Related `DataUnit` instances that may also be provided (and when they are, they must be kept in sync) (`frozenset`, read-only).
`primaryKey`	Full primary-key column name tuple.
`primaryKeyColumns`	Dictionary keyed on `primaryKey` names with `sqlalchemy.Column` entries into this `DataUnit` primary table as values (`dict`).
`regionColumn`	Table column (`sqlalchemy.Column`) with encoded region data, `None` if table has no region column.
`requiredDependencies`	Related `DataUnit` instances on which existence this `DataUnit` instance depends (`frozenset`, read-only).
`spatial`	Is this a spatial `DataUnitJoin`?
`table`	When not `None` the primary table entry corresponding to this `DataUnit` (`sqlalchemy.core.Table`, optional).

Methods Summary

validateId(dataId) Check if given dataId is valid.

Attributes Documentation

dependencies¶: The union of requiredDependencies and optionalDependencies (frozenset, read-only).

link¶: Names of columns that form the DataUnit specific part of the primary-key in this DataUnit table and are also the names of the link column in the Datasets table (tuple).

linkColumns¶: Dictionary keyed on link names with sqlalchemy.Column entries into this DataUnit primary table as values (dict).

name¶

Name of this DataUnit (str, read-only).

Also assumed to be the name of the primary table (if present).

optionalDependencies¶: Related DataUnit instances that may also be provided (and when they are, they must be kept in sync) (frozenset, read-only).

primaryKey¶: Full primary-key column name tuple. Consists of the link of this DataUnit and that of all its requiredDependencies (set).

primaryKeyColumns¶: Dictionary keyed on primaryKey names with sqlalchemy.Column entries into this DataUnit primary table as values (dict).

regionColumn¶: Table column (sqlalchemy.Column) with encoded region data, None if table has no region column.

requiredDependencies¶: Related DataUnit instances on which existence this DataUnit instance depends (frozenset, read-only).

table¶: When not None the primary table entry corresponding to this DataUnit (sqlalchemy.core.Table, optional).

Methods Documentation

validateId(dataId)¶

Check if given dataId is valid.

Parameters:	dataId : `dict` A `dict` of `DataUnit` link name, value pairs that label the `DatasetRef` within a Collection.
Raises:	ValueError If a value for a required dependency is missing.