ellipticity_from_cat¶
-
lsst.validate.drp.util.ellipticity_from_cat(cat, slot_shape='slot_Shape')¶ Calculate the ellipticity of the Shapes in a catalog from the 2nd moments.
- Parameters
- cat
lsst.afw.table.BaseCatalog A catalog with ‘slot_Shape’ defined and ‘_xx’, ‘_xy’, ‘_yy’ entries for the target of ‘slot_Shape’. E.g., ‘slot_shape’ defined as ‘base_SdssShape’ And ‘base_SdssShape_xx’, ‘base_SdssShape_xy’, ‘base_SdssShape_yy’ defined.
- slot_shapestr, optional
Specify what slot shape requested. Intended use is to get the PSF shape estimates by specifying ‘slot_shape=slot_PsfShape’ instead of the default ‘slot_shape=slot_Shape’.
- cat
- Returns
- e, e1, e2complex, float, float
Complex ellipticity, real part, imaginary part