ForcedPhotCcdTask¶

class lsst.meas.base.ForcedPhotCcdTask(butler=None, refSchema=None, **kwds)¶

Bases: lsst.meas.base.ForcedPhotImageTask

A command-line driver for performing forced measurement on CCD images.

Notes

This task is a subclass of lsst.meas.base.forcedPhotImage.ForcedPhotImageTask which is specifically for doing forced measurement on a single CCD exposure, using as a reference catalog the detections which were made on overlapping coadds.

The run method (inherited from ForcedPhotImageTask) takes a ButlerDataRef argument that corresponds to a single CCD. This should contain the data ID keys that correspond to the forced_src dataset (the output dataset for this task), which are typically all those used to specify the calexp dataset (visit, raft, sensor for LSST data) as well as a coadd tract. The tract is used to look up the appropriate coadd measurement catalogs to use as references (e.g. deepCoadd_src; see lsst.meas.base.references.CoaddSrcReferencesTask for more information). While the tract must be given as part of the dataRef, the patches are determined automatically from the bounding box and WCS of the calexp to be measured, and the filter used to fetch references is set via the filter option in the configuration of lsst.meas.base.references.BaseReferencesTask).

In addition to the run method, ForcedPhotCcdTask overrides several methods of ForcedPhotImageTask to specialize it for single-CCD processing, including makeIdFactory, fetchReferences, and getExposure. None of these should be called directly by the user, though it may be useful to override them further in subclasses.

Attributes Summary

`canMultiprocess`
`dataPrefix`

Methods Summary

`applyOverrides`(config)	A hook to allow a task to change the values of its config after the camera-specific overrides are loaded but before any command-line overrides are applied.
`attachFootprints`(sources, refCat, exposure, …)	Attach footprints to blank sources prior to measurements.
`emptyMetadata`()	Empty (clear) the metadata for this Task and all sub-Tasks.
`fetchReferences`(dataRef, exposure)	Get sources that overlap the exposure.
`getAllSchemaCatalogs`()	Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict.
`getExposure`(dataRef)	Read input exposure for measurement.
`getExposureId`(dataRef)
`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.
`getSchemaCatalogs`()	The schema catalogs that will be used 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.
`makeIdFactory`(dataRef)	Create an object that generates globally unique source IDs.
`makeSubtask`(name, **keyArgs)	Create a subtask as a new instance as the `name` attribute of this task.
`parseAndRun`([args, config, log, doReturnResults])	Parse an argument list and run the command.
`run`(measCat, exposure, refCat, refWcs[, …])	Perform forced measurement on a single exposure.
`runDataRef`(dataRef[, psfCache])	Perform forced measurement on a single exposure.
`timer`(name[, logLevel])	Context manager to log performance data for an arbitrary block of code.
`writeConfig`(butler[, clobber, doBackup])	Write the configuration used for processing the data, or check that an existing one is equal to the new one if present.
`writeMetadata`(dataRef)	Write the metadata produced from processing the data.
`writeOutput`(dataRef, sources)	Write forced source table
`writePackageVersions`(butler[, clobber, …])	Compare and write package versions.
`writeSchemas`(butler[, clobber, doBackup])	Write the schemas returned by `lsst.pipe.base.Task.getAllSchemaCatalogs`.

Attributes Documentation

canMultiprocess = True¶

dataPrefix = ''¶

Methods Documentation

classmethod applyOverrides(config)¶

A hook to allow a task to change the values of its config after the camera-specific overrides are loaded but before any command-line overrides are applied.

Parameters:	config : instance of task’s `ConfigClass` Task configuration.

Notes

This is necessary in some cases because the camera-specific overrides may retarget subtasks, wiping out changes made in ConfigClass.setDefaults. See LSST Trac ticket #2282 for more discussion.

Warning

This is called by CmdLineTask.parseAndRun; other ways of constructing a config will not apply these overrides.

attachFootprints(sources, refCat, exposure, refWcs, dataRef)¶

Attach footprints to blank sources prior to measurements.

Notes

Footprints for forced photometry must be in the pixel coordinate system of the image being measured, while the actual detections may start out in a different coordinate system.

Subclasses of this class must implement this method to define how those Footprints should be generated.

This default implementation transforms the Footprints from the reference catalog from the reference WCS to the exposure’s WcS, which downgrades lsst.afw.detection.heavyFootprint.HeavyFootprints into regular Footprints, destroying deblend information.

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

fetchReferences(dataRef, exposure)¶

Get sources that overlap the exposure.

Parameters:	dataRef : `lsst.daf.persistence.ButlerDataRef` Butler data reference corresponding to the image to be measured; should have `tract`, `patch`, and `filter` keys. exposure : `lsst.afw.image.Exposure` The image to be measured (used only to obtain a WCS and bounding box).
Returns:	referencs : `lsst.afw.table.SourceCatalog` Catalog of sources that overlap the exposure

Notes

The returned catalog is sorted by ID and guarantees that all included children have their parent included and that all Footprints are valid.

All work is delegated to the references subtask; see lsst.meas.base.references.CoaddSrcReferencesTask for information about the default behavior.

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.

getExposure(dataRef)¶

Read input exposure for measurement.

Parameters:	dataRef : `lsst.daf.persistence.ButlerDataRef` Butler data reference. Only the `calexp` dataset is used, unless `config.doApplyUberCal` is `True`, in which case the corresponding meas_mosaic outputs are used as well.

getExposureId(dataRef)¶

getFullMetadata()¶

Get metadata for all tasks.

Returns:	metadata : `lsst.daf.base.PropertySet` The `PropertySet` 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

getFullName

getSchemaCatalogs()¶

The schema catalogs that will be used by this task.

Returns:	schemaCatalogs : `dict` Dictionary mapping dataset type to schema catalog.

Notes

There is only one schema for each type of forced measurement. The dataset type for this measurement is defined in the mapper.

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("a brief description of what this task does")

makeIdFactory(dataRef)¶

Create an object that generates globally unique source IDs.

Source IDs are created based on a per-CCD ID and the ID of the CCD itself.

Parameters:	dataRef : `lsst.daf.persistence.ButlerDataRef` Butler data reference. The `ccdExposureId_bits` and `ccdExposureId` datasets are accessed. The data ID must have the keys that correspond to `ccdExposureId`, which are generally the same as those that correspond to `calexp` (`visit`, `raft`, `sensor` for LSST data).

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 pex_config ConfigurableField or RegistryField.

classmethod parseAndRun(args=None, config=None, log=None, doReturnResults=False)¶

Parse an argument list and run the command.

Parameters:

args : list, optional: List of command-line arguments; if None use sys.argv.
config : lsst.pex.config.Config-type, optional: Config for task. If None use Task.ConfigClass.
log : lsst.log.Log-type, optional: Log. If None use the default log.
doReturnResults : bool, optional: If True, return the results of this task. Default is False. This is only intended for unit tests and similar use. It can easily exhaust memory (if the task returns enough data and you call it enough times) and it will fail when using multiprocessing if the returned data cannot be pickled.

Returns:

struct : lsst.pipe.base.Struct

Fields are:

argumentParser: the argument parser.
parsedCmd: the parsed command returned by the argument parser’s lsst.pipe.base.ArgumentParser.parse_args method.
taskRunner: the task runner used to run the task (an instance of Task.RunnerClass).
resultList: results returned by the task runner’s run method, one entry per invocation.

This will typically be a list of None unless doReturnResults is True; see Task.RunnerClass (TaskRunner by default) for more information.

Notes

Calling this method with no arguments specified is the standard way to run a command-line task from the command-line. For an example see pipe_tasks bin/makeSkyMap.py or almost any other file in that directory.

If one or more of the dataIds fails then this routine will exit (with a status giving the number of failed dataIds) rather than returning this struct; this behaviour can be overridden by specifying the --noExit command-line option.

run(measCat, exposure, refCat, refWcs, exposureId=None)¶

Perform forced measurement on a single exposure.

Parameters:

measCat : lsst.afw.table.SourceCatalog: The measurement catalog, based on the sources listed in the reference catalog.
exposure : lsst.afw.image.Exposure: The measurement image upon which to perform forced detection.
refCat : lsst.afw.table.SourceCatalog: The reference catalog of sources to measure.
refWcs : lsst.afw.image.SkyWcs: The WCS for the references.
exposureId : int: Optional unique exposureId used for random seed in measurement task.

Returns:

result : lsst.pipe.base.Struct

Structure with fields:

measCat: Catalog of forced measurement results (lsst.afw.table.SourceCatalog).

runDataRef(dataRef, psfCache=None)¶

Perform forced measurement on a single exposure.

Parameters:

dataRef : lsst.daf.persistence.ButlerDataRef: Passed to the references subtask to obtain the reference WCS, the getExposure method (implemented by derived classes) to read the measurment image, and the fetchReferences method to get the exposure and load the reference catalog (see :lsst-task`lsst.meas.base.references.CoaddSrcReferencesTask`). Refer to derived class documentation for details of the datasets and data ID keys which are used.
psfCache : int, optional: Size of PSF cache, or None. The size of the PSF cache can have a significant effect upon the runtime for complicated PSF models.

Notes

Sources are generated with generateMeasCat in the measurement subtask. These are passed to measurement’s run method, which fills the source catalog with the forced measurement results. The sources are then passed to the writeOutputs method (implemented by derived classes) which writes the outputs.

timer(name, logLevel=10000)¶

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 `lsst.log` level constant.

Navigation

ForcedPhotCcdTask¶