SkyPixDimension

class lsst.daf.butler.SkyPixDimension(name: str, pixelization: lsst.sphgeom.pixelization.Pixelization)

Bases: lsst.daf.butler.Dimension

A special Dimension subclass for hierarchical pixelizations of the sky.

Unlike most other dimensions, skypix dimension records are not stored in the database, as these records only contain an integer pixel ID and a region on the sky, and each of these can be computed directly from the other.

Parameters:

name : str

Name of the dimension. By convention, this is a lowercase string abbreviation for the pixelization followed by its integer level, such as “htm7”.

pixelization : sphgeom.Pixelization

Pixelization instance that can compute regions from IDs and IDs from points.

Methods Summary

hasTable()	Return True if this element is associated with a table (even if that table “belongs” to another element).
makeTableSpec()	Return a specification of the schema for the table corresponding to this element.

Methods Documentation

hasTable() → bool

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

Instances of the DimensionElement base class itself are always associated with tables.

makeTableSpec() → Optional[lsst.daf.butler.core.schema.TableSpec]

Return a specification of the schema for the table corresponding to this element.

This programmatically generates the primary and foreign key fields from the element’s dependencies and then appends any metadata fields.

Returns:

spec : TableSpec or None

Database-agnostic specification of the fields in this table.