DimensionPacker

class lsst.daf.butler.DimensionPacker(fixed: DataCoordinate, dimensions: DimensionGroup | DimensionGraph)

Bases: object

Class for going from DataCoordinate to packed integer ID and back.

An abstract base class for bidirectional mappings between a DataCoordinate and a packed integer ID.

Parameters:

fixedDataCoordinate

Expanded data ID for the dimensions whose values must remain fixed (to these values) in all calls to pack, and are used in the results of calls to unpack. Subclasses may ignore particular dimensions, and are permitted to require that fixed.hasRecords() return True.

dimensionsDimensionGroup or DimensionGraph

The dimensions of data IDs packed by this instance. Only DimensionGroup will be supported after v27.

Attributes Summary

dimensions	The dimensions of data IDs packed by this instance (DimensionGraph).
maxBits	Return The maximum number of nonzero bits in the packed ID.
universe	Graph containing all known dimensions (DimensionUniverse).

Methods Summary

pack([dataId, returnMaxBits])	Pack the given data ID into a single integer.
unpack(packedId)	Unpack an ID produced by pack into a full DataCoordinate.

Attributes Documentation

dimensions

The dimensions of data IDs packed by this instance (DimensionGraph).

After v27 this will be a DimensionGroup.

maxBits

Return The maximum number of nonzero bits in the packed ID.

This packed ID will be returned by pack (int).

Must be implemented by all concrete derived classes. May return None to indicate that there is no maximum.

universe

Graph containing all known dimensions (DimensionUniverse).

Methods Documentation

pack(dataId: DataCoordinate | Mapping[str, Any] | None = None, *, returnMaxBits: bool = False, **kwargs: Any) → tuple[int, int] | int

Pack the given data ID into a single integer.

Parameters:

dataIdDataId

Data ID to pack. Values for any keys also present in the “fixed” data ID passed at construction must be the same as the values passed at construction, but in general you must still specify those keys.

returnMaxBitsbool

If True, return a tuple of (packed, self.maxBits).

**kwargs

Additional keyword arguments are treated like additional key-value pairs in dataId.

Returns:

packedint

Packed integer ID.

maxBitsint, optional

Maximum number of nonzero bits in packed. Not returned unless returnMaxBits is True.

Notes

Should not be overridden by derived class (_pack should be overridden instead).

abstract unpack(packedId: int) → DataCoordinate

Unpack an ID produced by pack into a full DataCoordinate.

Must be implemented by all concrete derived classes.

Parameters:

packedIdint

The result of a call to pack on either self or an identically-constructed packer instance.

Returns:

dataIdDataCoordinate

Dictionary-like ID that uniquely identifies all covered dimensions.