SingleFrameClassificationSizeExtendednessPlugin

class lsst.meas.base.SingleFrameClassificationSizeExtendednessPlugin(config, name, schema, metadata)

Bases: SingleFramePlugin

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

configSingleFrameClassificationSizeExtendednessConfig

Plugin configuration.

namestr

Plugin name.

schemaSchema

The schema for the measurement output catalog. New fields will be added to hold measurements produced by this plugin.

metadataPropertySet

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.

Attributes Summary

FAILURE_BAD_SHAPE

Denotes failures due to bad shape (int).

Methods Summary

fail(measRecord[, error])	Record a failure of the measure or measureN method.
getExecutionOrder()	Get the relative execution order of this plugin.
measure(measRecord, exposure)	Measure the properties of a source on a single image.

Attributes Documentation

FAILURE_BAD_SHAPE = 1

Denotes failures due to bad shape (int).

Methods Documentation

fail(measRecord, error=None) → None

Record a failure of the measure or measureN method.

Parameters

measRecordlsst.afw.table.SourceRecord

Table record describing the source being measured.

errorMeasurementError, 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.

classmethod getExecutionOrder()

Get the relative execution order of this plugin.

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

measure(measRecord, exposure) → None

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

measRecordlsst.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.

exposurelsst.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.