BaseSkyMap¶
- class lsst.skymap.BaseSkyMap(config=None)¶
Bases:
object
A collection of overlapping Tracts that map part or all of the sky.
See TractInfo for more information.
- Parameters:
- config
BaseSkyMapConfig
orNone
(optional) The configuration for this SkyMap; if None use the default config.
- config
Notes
BaseSkyMap is an abstract base class. Subclasses must do the following: define
__init__
and have it construct the TractInfo objects and put them in__tractInfoList__
define__getstate__
and__setstate__
to allow pickling (the butler saves sky maps using pickle); see DodecaSkyMap for an example of how to do this. (Most of that code could be moved into this base class, but that would make it harder to handle older versions of pickle data.) define updateSha1 to add any subclass-specific state to the hash.All SkyMap subclasses must be conceptually immutable; they must always refer to the same set of mathematical tracts and patches even if the in- memory representation of those objects changes.
Attributes Summary
Methods Summary
findClosestTractPatchList
(coordList)Find closest tract and patches that overlap coordinates.
findTract
(coord)Find the tract whose center is nearest the specified coord.
findTractIdArray
(ra, dec[, degrees])Find array of tract IDs with vectorized operations (where supported).
findTractPatchList
(coordList)Find tracts and patches that overlap a region.
getSha1
()Return a SHA1 hash that uniquely identifies this SkyMap instance.
logSkyMapInfo
(log)Write information about a sky map to supplied log
register
(name, butler)Add skymap, tract, and patch Dimension entries to the given Gen3 Butler.
updateSha1
(sha1)Add subclass-specific state or configuration options to the SHA1.
Attributes Documentation
- SKYMAP_DATASET_TYPE_NAME = 'skyMap'¶
- SKYMAP_RUN_COLLECTION_NAME = 'skymaps'¶
Methods Documentation
- findClosestTractPatchList(coordList)¶
Find closest tract and patches that overlap coordinates.
- Parameters:
- coordList
lsst.geom.SpherePoint
List of ICRS sky coordinates to search for.
- coordList
- Returns:
- retList
list
list of (TractInfo, list of PatchInfo) for tracts and patches that contain, or may contain, the specified region. The list will be empty if there is no overlap.
- retList
- findTract(coord)¶
Find the tract whose center is nearest the specified coord.
- Parameters:
- coord
lsst.geom.SpherePoint
ICRS sky coordinate to search for.
- coord
- Returns:
- result
TractInfo
TractInfo of tract whose center is nearest the specified coord.
- result
Notes
If coord is equidistant between multiple sky tract centers then one is arbitrarily chosen.
The default implementation is not very efficient; subclasses may wish to override.
Warning
If tracts do not cover the whole sky then the returned tract may not include the coord.
- findTractIdArray(ra, dec, degrees=False)¶
Find array of tract IDs with vectorized operations (where supported).
If a given sky map does not support vectorized operations, then a loop over findTract will be called.
- Parameters:
- ra
numpy.ndarray
Array of Right Ascension. Units are radians unless degrees=True.
- dec
numpy.ndarray
Array of Declination. Units are radians unless degrees=True.
- degrees
bool
, optional Input ra, dec arrays are degrees if
True
.
- ra
- Returns:
- tractId
numpy.ndarray
Array of tract IDs
- tractId
Notes
If coord is equidistant between multiple sky tract centers then one is arbitrarily chosen.
Warning
If tracts do not cover the whole sky then the returned tract may not include the given ra/dec.
- findTractPatchList(coordList)¶
Find tracts and patches that overlap a region.
- Parameters:
- coordList
list
oflsst.geom.SpherePoint
List of ICRS sky coordinates to search for.
- coordList
- Returns:
Notes
Warning
This uses a naive algorithm that may find some tracts and patches that do not overlap the region (especially if the region is not a rectangle aligned along patch x, y).
- getSha1()¶
Return a SHA1 hash that uniquely identifies this SkyMap instance.
- Returns:
- sha1
bytes
A 20-byte hash that uniquely identifies this SkyMap instance.
- sha1
Notes
Subclasses should almost always override
updateSha1
instead of this function to add subclass-specific state to the hash.
- logSkyMapInfo(log)¶
Write information about a sky map to supplied log
- Parameters:
- log
logging.Logger
Log object that information about skymap will be written.
- log
- register(name, butler)¶
Add skymap, tract, and patch Dimension entries to the given Gen3 Butler.
- Parameters:
- name
str
The name of the skymap.
- butler
lsst.daf.butler.Butler
The butler to add to.
- name
- Raises:
- lsst.daf.butler.registry.ConflictingDefinitionError
Raised if a different skymap exists with the same name.
Notes
Registering the same skymap multiple times (with the exact same definition) is safe, but inefficient; most of the work of computing the rows to be inserted must be done first in order to check for consistency between the new skymap and any existing one.
Re-registering a skymap with different tract and/or patch definitions but the same summary information may not be detected as a conflict but will never result in updating the skymap; there is intentionally no way to modify a registered skymap (aside from manual administrative operations on the database), as it is hard to guarantee that this can be done without affecting reproducibility.
- updateSha1(sha1)¶
Add subclass-specific state or configuration options to the SHA1.
- Parameters:
- sha1
hashlib.sha1
A hashlib object on which
update
can be called to add additional state to the hash.
- sha1
Notes
This method is conceptually “protected” : it should be reimplemented by all subclasses, but called only by the base class implementation of
getSha1
.