GetCoaddAsTemplateTask

class lsst.ip.diffim.GetCoaddAsTemplateTask(config: Config | None = None, name: str | None = None, parentTask: Task | None = None, log: logging.Logger | lsst.utils.logging.LsstLogAdapter | None = None)

Bases: Task

Subtask to retrieve coadd for use as an image difference template.

This is the default getTemplate Task to be run as a subtask by pipe.tasks.ImageDifferenceTask. The main methods are run() and runGen3().

Notes

From the given skymap, the closest tract is selected; multiple tracts are not supported. The assembled template inherits the WCS of the selected skymap tract and the resolution of the template exposures. Overlapping box regions of the input template patches are pixel by pixel copied into the assembled template image. There is no warping or pixel resampling.

Pixels with no overlap of any available input patches are set to nan value and NO_DATA flagged.

Methods Summary

emptyMetadata()	Empty (clear) the metadata for this Task and all sub-Tasks.
getAllSchemaCatalogs()	Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict.
getCoaddDatasetName()	Return coadd name for given task config
getFullMetadata()	Get metadata for all tasks.
getFullName()	Get the task name as a hierarchical name including parent task names.
getName()	Get the name of the task.
getOverlapPatchList(exposure, skyMap)	Select the relevant tract and its patches that overlap with the science exposure.
getSchemaCatalogs()	Get the schemas generated by this task.
getTaskDict()	Get a dictionary of all tasks as a shallow copy.
makeField(doc)	Make a lsst.pex.config.ConfigurableField for this task.
makeSubtask(name, **keyArgs)	Create a subtask as a new instance as the name attribute of this task.
run(tractInfo, patchList, skyCorners, ...[, ...])	Gen2 and gen3 shared code: determination of exposure dimensions and copying of pixels from overlapping patch regions.
runDataRef(exposure, sensorRef[, templateIdList])	Gen2 task entry point.
runQuantum(exposure, butlerQC, skyMapRef, ...)	Gen3 task entry point.
timer(name[, logLevel])	Context manager to log performance data for an arbitrary block of code.

Methods Documentation

emptyMetadata() → None

Empty (clear) the metadata for this Task and all sub-Tasks.

getAllSchemaCatalogs() → Dict[str, Any]

Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict.

Returns:

schemacatalogsdict

Keys are butler dataset type, values are a empty catalog (an instance of the appropriate lsst.afw.table Catalog type) for all tasks in the hierarchy, from the top-level task down through all subtasks.

Notes

This method may be called on any task in the hierarchy; it will return the same answer, regardless.

The default implementation should always suffice. If your subtask uses schemas the override Task.getSchemaCatalogs, not this method.

getCoaddDatasetName()

Return coadd name for given task config

Returns:

CoaddDatasetNamestring

TODO: This nearly duplicates a method in CoaddBaseTask (DM-11985)

getFullMetadata() → TaskMetadata

Get metadata for all tasks.

Returns:

metadataTaskMetadata

The keys are the full task name. Values are metadata for the top-level task and all subtasks, sub-subtasks, etc.

Notes

The returned metadata includes timing information (if @timer.timeMethod is used) and any metadata set by the task. The name of each item consists of the full task name with . replaced by :, followed by . and the name of the item, e.g.:

topLevelTaskName:subtaskName:subsubtaskName.itemName

using : in the full task name disambiguates the rare situation that a task has a subtask and a metadata item with the same name.

getFullName() → str

Get the task name as a hierarchical name including parent task names.

Returns:

fullNamestr

The full name consists of the name of the parent task and each subtask separated by periods. For example:

• The full name of top-level task “top” is simply “top”.

• The full name of subtask “sub” of top-level task “top” is “top.sub”.

• The full name of subtask “sub2” of subtask “sub” of top-level task “top” is “top.sub.sub2”.

getName() → str

Get the name of the task.

Returns:

taskNamestr

Name of the task.

See also

getFullName

getOverlapPatchList(exposure, skyMap)

Select the relevant tract and its patches that overlap with the science exposure.

Parameters:

exposurelsst.afw.image.Exposure

The science exposure to define the sky region of the template coadd.

skyMaplsst.skymap.BaseSkyMap

SkyMap object that corresponds to the template coadd.

Returns:

resulttuple of

• tractInfolsst.skymap.TractInfo

  The selected tract.

• patchListlist of lsst.skymap.PatchInfo

  List of all overlap patches of the selected tract.

• skyCornerslist of lsst.geom.SpherePoint

  Corners of the exposure in the sky in the order given by lsst.geom.Box2D.getCorners.

getSchemaCatalogs() → Dict[str, Any]

Get the schemas generated by this task.

Returns:

schemaCatalogsdict

Keys are butler dataset type, values are an empty catalog (an instance of the appropriate lsst.afw.table Catalog type) for this task.

See also

Task.getAllSchemaCatalogs

Notes

Warning

Subclasses that use schemas must override this method. The default implementation returns an empty dict.

This method may be called at any time after the Task is constructed, which means that all task schemas should be computed at construction time, not when data is actually processed. This reflects the philosophy that the schema should not depend on the data.

Returning catalogs rather than just schemas allows us to save e.g. slots for SourceCatalog as well.

getTaskDict() → Dict[str, ReferenceType[Task]]

Get a dictionary of all tasks as a shallow copy.

Returns:

taskDictdict

Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc.

classmethod makeField(doc: str) → ConfigurableField

Make a lsst.pex.config.ConfigurableField for this task.

Parameters:

docstr

Help text for the field.

Returns:

configurableFieldlsst.pex.config.ConfigurableField

A ConfigurableField for this task.

Examples

Provides a convenient way to specify this task is a subtask of another task.

Here is an example of use:

class OtherTaskConfig(lsst.pex.config.Config):
    aSubtask = ATaskClass.makeField("brief description of task")

makeSubtask(name: str, **keyArgs: Any) → None

Create a subtask as a new instance as the name attribute of this task.

Parameters:

namestr

Brief name of the subtask.

keyArgs

Extra keyword arguments used to construct the task. The following arguments are automatically provided and cannot be overridden:

• “config”.

• “parentTask”.

Notes

The subtask must be defined by Task.config.name, an instance of ConfigurableField or RegistryField.

run(tractInfo, patchList, skyCorners, availableCoaddRefs, sensorRef=None, visitInfo=None)

Gen2 and gen3 shared code: determination of exposure dimensions and copying of pixels from overlapping patch regions.

Parameters:

skyMaplsst.skymap.BaseSkyMap

SkyMap object that corresponds to the template coadd.

tractInfolsst.skymap.TractInfo

The selected tract.

patchListiterable of lsst.skymap.patchInfo.PatchInfo

Patches to consider for making the template exposure.

skyCornerslist of lsst.geom.SpherePoint

Sky corner coordinates to be covered by the template exposure.

availableCoaddRefsdict [int]

Dictionary of spatially relevant retrieved coadd patches, indexed by their sequential patch number. In Gen3 mode, values are lsst.daf.butler.DeferredDatasetHandle and .get() is called, in Gen2 mode, sensorRef.get(**coaddef) is called to retrieve the coadd.

sensorReflsst.daf.persistence.ButlerDataRef, Gen2 only

Butler data reference to get coadd data. Must be None for Gen3.

visitInfolsst.afw.image.VisitInfo, Gen2 only

VisitInfo to make dcr model.

Returns:

templateExposure: lsst.afw.image.ExposureF

The created template exposure.

runDataRef(exposure, sensorRef, templateIdList=None)

Gen2 task entry point. Retrieve and mosaic a template coadd exposure that overlaps the science exposure.

Parameters:

exposure: `lsst.afw.image.Exposure`

an exposure for which to generate an overlapping template

sensorRefTYPE

a Butler data reference that can be used to obtain coadd data

templateIdListTYPE, optional

list of data ids, unused here, in the case of coadd template

Returns:

resultlsst.pipe.base.Struct

• exposurelsst.afw.image.ExposureF

  a template coadd exposure assembled out of patches

• sources : None for this subtask

runQuantum(exposure, butlerQC, skyMapRef, coaddExposureRefs)

Gen3 task entry point. Retrieve and mosaic a template coadd exposure that overlaps the science exposure.

Parameters:

exposurelsst.afw.image.Exposure

The science exposure to define the sky region of the template coadd.

butlerQClsst.pipe.base.ButlerQuantumContext

Butler like object that supports getting data by DatasetRef.

skyMapReflsst.daf.butler.DatasetRef

Reference to SkyMap object that corresponds to the template coadd.

coaddExposureRefsiterable of lsst.daf.butler.DeferredDatasetRef

Iterable of references to the available template coadd patches.

Returns:

resultlsst.pipe.base.Struct

• exposurelsst.afw.image.ExposureF

  a template coadd exposure assembled out of patches

• sources : None for this subtask

timer(name: str, logLevel: int = 10) → Iterator[None]

Context manager to log performance data for an arbitrary block of code.

Parameters:

namestr

Name of code being timed; data will be logged using item name: Start and End.

logLevel

A logging level constant.

See also

timer.logInfo

Examples

Creating a timer context:

with self.timer("someCodeToTime"):
    pass  # code to time