MakeKernelTask

class lsst.ip.diffim.MakeKernelTask(*args, **kwargs)

Bases: PsfMatchTask

Construct a kernel for PSF matching two exposures.

Methods Summary

emptyMetadata()

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

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.

getSelectSources(exposure[, sigma, ...])

Get sources to use for Psf-matching.

getTaskDict()

Get a dictionary of all tasks as a shallow copy.

makeCandidateList(templateExposure, ...[, ...])

Make a list of acceptable KernelCandidates.

makeField(doc)

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

makeKernelBasisList([targetFwhmPix, ...])

Wrapper to set log messages for lsst.ip.diffim.makeKernelBasisList.

makeSubtask(name, **keyArgs)

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

run(template, science, kernelSources[, ...])

Solve for the kernel and background model that best match two Exposures evaluated at the given source locations.

selectKernelSources(template, science[, ...])

Select sources from a list of candidates, and extract footprints.

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.

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
getSelectSources(exposure, sigma=None, doSmooth=True, idFactory=None)

Get sources to use for Psf-matching.

This method runs detection and measurement on an exposure. The returned set of sources will be used as candidates for Psf-matching.

Parameters:
exposurelsst.afw.image.Exposure

Exposure on which to run detection/measurement

sigmafloat, optional

PSF sigma, in pixels, used for smoothing the image for detection. If None, the PSF width will be used.

doSmoothbool

Whether or not to smooth the Exposure with Psf before detection

idFactorylsst.afw.table.IdFactory

Factory for the generation of Source ids

Returns:
selectSources

source catalog containing candidates for the Psf-matching

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.

makeCandidateList(templateExposure, scienceExposure, kernelSize, candidateList=None, preconvolved=False)

Make a list of acceptable KernelCandidates.

Accept or generate a list of candidate sources for Psf-matching, and examine the Mask planes in both of the images for indications of bad pixels

Parameters:
templateExposurelsst.afw.image.Exposure

Exposure that will be convolved

scienceExposurelsst.afw.image.Exposure

Exposure that will be matched-to

kernelSizefloat

Dimensions of the Psf-matching Kernel, used to grow detection footprints

candidateListlist, optional

List of Sources to examine. Elements must be of type afw.table.Source or a type that wraps a Source and has a getSource() method, such as meas.algorithms.PsfCandidateF.

preconvolvedbool, optional

Was the science exposure already convolved with its PSF?

Returns:
candidateListlist of dict

A list of dicts having a “source” and “footprint” field for the Sources deemed to be appropriate for Psf matching.

Raises:
RuntimeError

If candidateList is empty or contains incompatible types.

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")
makeKernelBasisList(targetFwhmPix=None, referenceFwhmPix=None, basisDegGauss=None, basisSigmaGauss=None, metadata=None)

Wrapper to set log messages for lsst.ip.diffim.makeKernelBasisList.

Parameters:
targetFwhmPixfloat, optional

Passed on to lsst.ip.diffim.generateAlardLuptonBasisList. Not used for delta function basis sets.

referenceFwhmPixfloat, optional

Passed on to lsst.ip.diffim.generateAlardLuptonBasisList. Not used for delta function basis sets.

basisDegGausslist of int, optional

Passed on to lsst.ip.diffim.generateAlardLuptonBasisList. Not used for delta function basis sets.

basisSigmaGausslist of int, optional

Passed on to lsst.ip.diffim.generateAlardLuptonBasisList. Not used for delta function basis sets.

metadatalsst.daf.base.PropertySet, optional

Passed on to lsst.ip.diffim.generateAlardLuptonBasisList. Not used for delta function basis sets.

Returns:
basisList: list of lsst.afw.math.kernel.FixedKernel

List of basis kernels.

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(template, science, kernelSources, preconvolved=False)

Solve for the kernel and background model that best match two Exposures evaluated at the given source locations.

Parameters:
templatelsst.afw.image.Exposure

Exposure that will be convolved.

sciencelsst.afw.image.Exposure

The exposure that will be matched.

kernelSourceslist of dict

A list of dicts having a “source” and “footprint” field for the Sources deemed to be appropriate for Psf matching. Can be the output from selectKernelSources.

preconvolvedbool, optional

Was the science image convolved with its own PSF?

Returns:
resultslsst.pipe.base.Struct
psfMatchingKernellsst.afw.math.LinearCombinationKernel

Spatially varying Psf-matching kernel.

backgroundModellsst.afw.math.Function2D

Spatially varying background-matching function.

selectKernelSources(template, science, candidateList=None, preconvolved=False)

Select sources from a list of candidates, and extract footprints.

Parameters:
templatelsst.afw.image.Exposure

Exposure that will be convolved.

sciencelsst.afw.image.Exposure

The exposure that will be matched.

candidateListlist, optional

List of Sources to examine. Elements must be of type afw.table.Source or a type that wraps a Source and has a getSource() method, such as meas.algorithms.PsfCandidateF.

preconvolvedbool, optional

Was the science image convolved with its own PSF?

Returns:
kernelSourceslist of dict

A list of dicts having a “source” and “footprint” field for the Sources deemed to be appropriate for Psf matching.

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