_source.py

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# This file is part of afw.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (https://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
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__all__ = []

from lsst.utils import continueClass
from ._base import Catalog
from ._table import SourceCatalog, SourceTable

Catalog.register("Source", SourceCatalog)


@continueClass  # noqa: F811
class SourceCatalog:

    def getChildren(self, parent, *args):
        """Return the subset of self for which the parent field equals the given value.

        In order for this method to return the correct result, it must be sorted by parent
        (i.e. self.isSorted(SourceTable.getParentKey()) must be True).  This is naturally the
        case with SourceCatalogs produced by the detection and deblending tasks, but it may
        not be true when concatenating multiple such catalogs.

        Additional Catalogs or sequences whose elements correspond in order to the records
        of self (i.e. zip(self, *args) is valid) will be subset using the same slice object
        used on self, and these subsets will be returned along with the subset of self.

        Parameters
        ----------
        parent : `int`
            ID of the parent to get children for.
        args : `~lsst.afw.table.Catalog`
            Additional catalogs to subset for the childrens to return.

        Returns
        -------
        children : iterable of `~lsst.afw.table.SourceRecord`
            Children sources.
        """
        if not self.isSorted(SourceTable.getParentKey()):
            raise AssertionError(
                "The table is not sorted by parent, so cannot getChildren")
        s = self.equal_range(parent, SourceTable.getParentKey())
        if args:
            return (self[s],) + tuple(arg[s] for arg in args)
        else:
            return self[s]