GetCoaddAsTemplateTask¶

class lsst.ip.diffim.GetCoaddAsTemplateTask(config=None, name=None, parentTask=None, log=None)¶

Bases: lsst.pipe.base.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()¶: 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.

Returns:	schemacatalogs : `dict` 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:	CoaddDatasetName : `string` TODO: This nearly duplicates a method in CoaddBaseTask (DM-11985)

getFullMetadata()¶

Get metadata for all tasks.

Returns:	metadata : `lsst.daf.base.PropertySet` or `TaskMetadata` 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()¶

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

Returns:	fullName : `str` 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()¶

Get the name of the task.

Returns:	taskName : `str` Name of the 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()¶

Get a dictionary of all tasks as a shallow copy.

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

classmethod makeField(doc)¶

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

Parameters:	doc : `str` Help text for the field.
Returns:	configurableField : `lsst.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, **keyArgs)¶

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

Parameters:	name : `str` 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:

skyMap : lsst.skymap.BaseSkyMap: SkyMap object that corresponds to the template coadd.
tractInfo : lsst.skymap.TractInfo: The selected tract.
patchList : iterable of lsst.skymap.PatchInfo: Patches to consider for making the template exposure.
skyCorners : list of lsst.geom.SpherePoint: Sky corner coordinates to be covered by the template exposure.
availableCoaddRefs : dict [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.
sensorRef : lsst.daf.persistence.ButlerDataRef, Gen2 only: Butler data reference to get coadd data. Must be None for Gen3.
visitInfo : lsst.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 sensorRef : TYPE a Butler data reference that can be used to obtain coadd data templateIdList : TYPE, optional list of data ids, unused here, in the case of coadd template
Returns:	result : `lsst.pipe.base.Struct` `exposure` : `lsst.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:

exposure : lsst.afw.image.Exposure: The science exposure to define the sky region of the template coadd.
butlerQC : lsst.pipe.base.ButlerQuantumContext: Butler like object that supports getting data by DatasetRef.
skyMapRef : lsst.daf.butler.DatasetRef: Reference to SkyMap object that corresponds to the template coadd.
coaddExposureRefs : iterable of lsst.daf.butler.DeferredDatasetRef: Iterable of references to the available template coadd patches.

Returns:

result : lsst.pipe.base.Struct

exposure : lsst.afw.image.ExposureF

a template coadd exposure assembled out of patches
sources : None for this subtask

timer(name, logLevel=10)¶

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

Parameters:	name : `str` Name of code being timed; data will be logged using item name: `Start` and `End`. logLevel A `logging` level constant.

Parameters:	exposure : `lsst.afw.image.Exposure` The science exposure to define the sky region of the template coadd. skyMap : `lsst.skymap.BaseSkyMap` SkyMap object that corresponds to the template coadd.
Returns:	result : `tuple` of `tractInfo` : `lsst.skymap.TractInfo` The selected tract. `patchList` : `list` of `lsst.skymap.PatchInfo` List of all overlap patches of the selected tract. `skyCorners` : `list` of `lsst.geom.SpherePoint` Corners of the exposure in the sky in the order given by `lsst.geom.Box2D.getCorners`.

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GetCoaddAsTemplateTask¶