PostprocessAnalysis

class lsst.pipe.tasks.postprocess.PostprocessAnalysis(parq, functors, filt=None, flags=None, refFlags=None, forcedFlags=None)

Bases: object

Calculate columns from ParquetTable.

This object manages and organizes an arbitrary set of computations on a catalog. The catalog is defined by a ParquetTable object (or list thereof), such

as a deepCoadd_obj dataset, and the computations are defined by a

collection of lsst.pipe.tasks.functor.Functor objects (or, equivalently, a CompositeFunctor).

After the object is initialized, accessing the .df attribute (which holds the pandas.DataFrame containing the results of the calculations) triggers computation of said dataframe.

One of the conveniences of using this object is the ability to define a desired common filter for all functors. This enables the same functor collection to be passed to several different PostprocessAnalysis objects without having to change the original functor collection, since the filt keyword argument of this object triggers an overwrite of the filt property for all functors in the collection.

This object also allows a list of refFlags to be passed, and defines a set of default refFlags that are always included even if not requested.

If a list of ParquetTable object is passed, rather than a single one, then the calculations will be mapped over all the input catalogs. In principle, it should be straightforward to parallelize this activity, but initial tests have failed (see TODO in code comments).

Parameters:

parq : ParquetTable (or list of such)

Source catalog(s) for computation.

functors : list, dict, or CompositeFunctor

Computations to do (functors that act on parq). If a dict, the output DataFrame will have columns keyed accordingly. If a list, the column keys will come from the .shortname attribute of each functor.

filt : str, optional

Filter in which to calculate. If provided, this will overwrite any existing .filt attribute of the provided functors.

flags : list, optional

List of flags (per-band) to include in output table. Taken from the meas dataset if applied to a multilevel Object Table.

refFlags : list, optional

List of refFlags (only reference band) to include in output table.

forcedFlags : list, optional

List of flags (per-band) to include in output table. Taken from the forced_src dataset if applied to a multilevel Object Table. Intended for flags from measurement plugins only run during multi-band forced-photometry.

Attributes Summary

defaultFuncs
df
func
noDupCols

Methods Summary

compute([dropna, pool])

Attributes Documentation

defaultFuncs

df

func

noDupCols

Methods Documentation

compute(dropna=False, pool=None)