Inheritance diagram for lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin:

Public Member Functions
	getExecutionOrder (cls)

	__init__ (self, config, name, schema, metadata)

None	measure (self, measRecord, exposure)

None	fail (self, measRecord, error=None)

Public Attributes
	key

	flag

	FAILURE_BAD_SHAPE

Static Public Attributes
	ConfigClass = SingleFrameMomentsClassifierConfig

int	FAILURE_BAD_SHAPE = 1

Detailed Description

Classify objects by comparing their moments-based trace radius to PSF's.

The plugin computes chi^2 as ((T_obj - T_psf)/T_psf^exponent)^2, where
T_obj is the sum of Ixx and Iyy moments of the object, and T_psf is the
sum of Ixx and Iyy moments of the PSF. The exponent is configurable.
The measure of being a galaxy is then 1 - exp(-0.5*chi^2).

Parameters
----------
config : `MomentsClassifierConfig`
    Plugin configuration.
name : `str`
    Plugin name.
schema : `~lsst.afw.table.Schema`
    The schema for the measurement output catalog. New fields will be
    added to hold measurements produced by this plugin.
metadata : `~lsst.daf.base.PropertySet`
    Plugin metadata that will be attached to the output catalog.

Notes
-----
The ``measure`` method of the plugin requires a value for the ``exposure``
argument to maintain consistent API, but it is not used in the measurement.

Definition at line 660 of file plugins.py.

Constructor & Destructor Documentation

◆ init()

lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.__init__	(	self,
		config,
		name,
		schema,
		metadata )

Reimplemented from lsst.meas.base.sfm.SingleFramePlugin.

Definition at line 696 of file plugins.py.

    def __init__(self, config, name, schema, metadata):
        SingleFramePlugin.__init__(self, config, name, schema, metadata)
        self.key = schema.addField(name + "_value",
                                   type="D",
                                   doc="Measure of being a galaxy based on trace of second order moments",
                                   )
        self.flag = schema.addField(name + "_flag", type="Flag", doc="Moments-based classification failed")
 

Member Function Documentation

◆ fail()

None lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.fail	(	self,
		measRecord,
		error = None )

Record a failure of the `measure` or `measureN` method.

Parameters
----------
measRecord : `lsst.afw.table.SourceRecord`
    Table record describing the source being measured.
error : `MeasurementError`, optional
    Only provided if the measurement failed due to a
    `MeasurementError` being raised; otherwise, will be `None`.

Notes
-----
When the plugin raises an exception, framework will call
`BasePlugin.fail` to allow the plugin to set its failure flag
field(s).  When `BasePlugin.measureN` raises an exception,
`BasePlugin.fail` will be called repeatedly with all the records that
were being measured.

If the exception is an `MeasurementError`, it will be passed as the
error argument; in all other cases the error argument will be `None`,
and the failure will be logged by the measurement framework as a
warning.

Reimplemented from lsst.meas.base.pluginsBase.BasePlugin.

Definition at line 728 of file plugins.py.

    def fail(self, measRecord, error=None) -> None:
        # Docstring inherited.
        measRecord.set(self.key, np.nan)
        measRecord.set(self.flag, True)
 
 

◆ getExecutionOrder()

lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.getExecutionOrder ( cls )

Get the relative execution order of this plugin.

Must be reimplemented as a class method by concrete derived classes.

Reimplemented from lsst.meas.base.pluginsBase.BasePlugin.

Definition at line 693 of file plugins.py.

    def getExecutionOrder(cls):
        return cls.FLUX_ORDER
 

◆ measure()

None lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.measure	(	self,
		measRecord,
		exposure )

Measure the properties of a source on a single image.

The image may be from a single epoch, or it may be a coadd.

Parameters
----------
measRecord : `lsst.afw.table.SourceRecord`
    Record describing the object being measured. Previously-measured
    quantities may be retrieved from here, and it will be updated
    in-place tih the outputs of this plugin.
exposure : `lsst.afw.image.ExposureF`
    The pixel data to be measured, together with the associated PSF,
    WCS, etc. All other sources in the image should have been replaced
    by noise according to deblender outputs.

Reimplemented from lsst.meas.base.sfm.SingleFramePlugin.

Definition at line 704 of file plugins.py.

    def measure(self, measRecord, exposure) -> None:
        # Docstring inherited.
 
        if measRecord.getShapeFlag():
            raise MeasurementError(
                "Shape flag is set.  Required for " + self.name + " algorithm",
                self.FAILURE_BAD_SHAPE,
            )
 
        shape = measRecord.getShape()
        psf_shape = measRecord.getPsfShape()
 
        ixx = shape.getIxx()
        iyy = shape.getIyy()
        ixx_psf = psf_shape.getIxx()
        iyy_psf = psf_shape.getIyy()
 
        object_t = ixx + iyy
        psf_t = ixx_psf + iyy_psf
 
        chi_sq = ((object_t - psf_t)/(psf_t**self.config.exponent))**2.
        likelihood = 1. - np.exp(-0.5*chi_sq)
        measRecord.set(self.key, likelihood)
 

Member Data Documentation

◆ ConfigClass

lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.ConfigClass = SingleFrameMomentsClassifierConfig

static

Definition at line 686 of file plugins.py.

◆ FAILURE_BAD_SHAPE [1/2]

int lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.FAILURE_BAD_SHAPE = 1

static

Definition at line 688 of file plugins.py.

◆ FAILURE_BAD_SHAPE [2/2]

lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.FAILURE_BAD_SHAPE

Definition at line 710 of file plugins.py.

◆ flag

lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.flag

Definition at line 702 of file plugins.py.

◆ key

lsst.meas.base.plugins.SingleFrameMomentsClassifierPlugin.key

Definition at line 698 of file plugins.py.

The documentation for this class was generated from the following file:

/j/snowflake/release/lsstsw/stack/lsst-scipipe-8.0.0/Linux64/meas_base/g48712c4677+72a8b1060b/python/lsst/meas/base/plugins.py

Public Member Functions

Public Attributes

Static Public Attributes