CalcE2

class lsst.analysis.tools.actions.vector.CalcE2(*args, **kw)

Bases: VectorAction

Calculate \(e_2\) (distortion-type) or \(g_2\) (shear-type).

The definitions are as follows:

\[\begin{split}e_2 &= 2I_{xy}/(I_{xx}+I_{yy}) \\ g_2 &= 2I_{xy}/(I_{xx}+I_{yy}+2\sqrt{(I_{xx}I_{yy}-I_{xy}^{2})}).\end{split}\]

See also

CalcE

CalcE1

Notes

This is a shape measurement used for doing QA on the ellipticity of the sources.

Attributes Summary

colXx	The column name to get the xx shape component from.
colXy	The column name to get the xy shape component from.
colYy	The column name to get the yy shape component from.
ellipticityType	The type of ellipticity to calculate (str, default 'distortion')

Methods Summary

__call__(data, **kwargs)	Call self as a function.
getInputSchema()	Return the schema an AnalysisAction expects to be present in the arguments supplied to the __call__ method.

Attributes Documentation

colXx

The column name to get the xx shape component from. (str, default '{band}_ixx')

colXy

The column name to get the xy shape component from. (str, default '{band}_ixy')

colYy

The column name to get the yy shape component from. (str, default '{band}_iyy')

ellipticityType

The type of ellipticity to calculate (str, default 'distortion')

Allowed values:

'distortion'

Distortion, defined as \(2I_{xy}/(I_{xx}+I_{yy})\)

'shear'

Shear, defined as \(2I_{xy}/(I_{xx}+I_{yy}+2\sqrt{I_{xx}I_{yy}-I_{xy}^2})\)

Methods Documentation

__call__(data: MutableMapping[str, ndarray[Any, dtype[ScalarType]] | Scalar | HealSparseMap], **kwargs) → ndarray[Any, dtype[ScalarType]]

Call self as a function.

getInputSchema() → HealSparseMap]]]

Return the schema an AnalysisAction expects to be present in the arguments supplied to the __call__ method.

Returns:

resultKeyedDataSchema

The schema this action requires to be present when calling this action, keys are unformatted.