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Tickets/dm 6077 #56

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Jun 7, 2016
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Tickets/dm 6077 #56

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0a06739
Improve documentation for MeasurePsfTask
r-owen Jun 6, 2016
782ac0a
Construct the psf determiner as a subtask
r-owen Jun 6, 2016
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54 changes: 23 additions & 31 deletions python/lsst/pipe/tasks/measurePsf.py
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,8 @@ class MeasurePsfConfig(pexConfig.Config):
)
reserveSeed = pexConfig.Field(
dtype = int,
doc = "This number will be multplied by the exposure ID to set the random seed for reserving candidates",
doc = "This number will be multiplied by the exposure ID "
"to set the random seed for reserving candidates",
default = 1,
)

Expand Down Expand Up @@ -69,24 +70,12 @@ class MeasurePsfTask(pipeBase.Task):

\section pipe_tasks_measurePsf_Purpose Description

A task that wraps two algorithms set via a pair of registries specified in the task's
\ref pipe_tasks_measurePsf_Config.
Both algorithms are classes with a constructor taking a pex.config.Config object (\em e.g.
lsst.meas.algorithms.objectSizeStarSelector.ObjectSizeStarSelector.__init__).
A task that selects stars from a catalog of sources and uses those to measure the PSF.

The algorithms are:
- a star selector, a subclass of lsst.meas.algorithms.StarSelector.selectStars

- a psf estimator with API:
\code
determinePsf(exposure, psfCandidateList, metadata=None, flagKey=None)
\endcode
which returns an lsst.afw.detection.Psf and lsst.afw.math.SpatialCellSet (\em e.g.
lsst.meas.algorithms.pcaPsfDeterminer.PcaPsfDeterminer.determinePsf).
MeasurePsfTask calls determinePsf with \c flagKey set to
"calib.psf.used" if a schema is passed to its constructor (see \ref pipe_tasks_measurePsf_Initialize).

See also lsst.meas.algorithms.psfDeterminerRegistry.psfDeterminerRegistry.
The star selector is a subclass of
\ref lsst.meas.algorithms.starSelector.StarSelectorTask "lsst.meas.algorithms.StarSelectorTask"
and the PSF determiner is a sublcass of
\ref lsst.meas.algorithms.psfDeterminer.PsfDeterminerTask "lsst.meas.algorithms.PsfDeterminerTask"
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Should be lsst.meas.algorithms.BasePsfDeterminerTask

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Yes. I pushed that fix after I asked you to review it and am a bit worried you are still seeing the older version.


\warning
There is no establised set of configuration parameters for these algorithms, so once you start modifying
Expand Down Expand Up @@ -136,7 +125,8 @@ class MeasurePsfTask(pipeBase.Task):
\endcode
\dontinclude measurePsfTask.py

The example also runs SourceDetectionTask and SourceMeasurementTask; see \ref meas_algorithms_measurement_Example for more explanation.
The example also runs SourceDetectionTask and SourceMeasurementTask;
see \ref meas_algorithms_measurement_Example for more explanation.

Import the tasks (there are some other standard imports; read the file to see them all):

Expand Down Expand Up @@ -251,20 +241,22 @@ def __init__(self, schema=None, **kwargs):
def run(self, exposure, sources, expId=0, matches=None):
"""!Measure the PSF

\param[in,out] exposure Exposure to process; measured PSF will be added.
\param[in,out] sources Measured sources on exposure; flag fields will be set marking
stars chosen by the star selector and the PSF determiner if a schema
was passed to the task constructor.
\param[in] expId Exposure id used for generating random seed.
\param[in] matches a list of lsst.afw.table.ReferenceMatch objects (\em i.e. of lsst.afw.table.Match
with \c first being of type lsst.afw.table.SimpleRecord and \c second
type lsst.afw.table.SourceRecord --- the reference object and detected
object respectively) as returned by \em e.g. the AstrometryTask.
Used by star selectors that choose to refer to an external catalog.
\param[in,out] exposure Exposure to process; measured PSF will be added.
\param[in,out] sources Measured sources on exposure; flag fields will be set marking
stars chosen by the star selector and the PSF determiner if a schema
was passed to the task constructor.
\param[in] expId Exposure id used for generating random seed.
\param[in] matches A list of lsst.afw.table.ReferenceMatch objects
(\em i.e. of lsst.afw.table.Match
with \c first being of type lsst.afw.table.SimpleRecord and \c second
type lsst.afw.table.SourceRecord --- the reference object and detected
object respectively) as returned by \em e.g. the AstrometryTask.
Used by star selectors that choose to refer to an external catalog.

\return a pipe.base.Struct with fields:
- psf: The measured PSF (also set in the input exposure)
- cellSet: an lsst.afw.math.SpatialCellSet containing the PSF candidates as returned by the psf determiner.
- cellSet: an lsst.afw.math.SpatialCellSet containing the PSF candidates
as returned by the psf determiner.
"""
self.log.info("Measuring PSF")

Expand All @@ -287,7 +279,7 @@ def run(self, exposure, sources, expId=0, matches=None):

if self.config.reserveFraction > 0 :
random.seed(self.config.reserveSeed*expId)
reserveList = random.sample(psfCandidateList,
reserveList = random.sample(psfCandidateList,
int((self.config.reserveFraction)*len(psfCandidateList)))

for cand in reserveList:
Expand Down