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lsst.afw g4f4f280218+81551fceaa
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Public Member Functions | |
| def | getChildren (self, parent, *args) |
Definition at line 33 of file _source.py.
| def lsst.afw.table._source.SourceCatalog.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` or `iterable` of `int`
ID(s) of the parent(s) to get children for.
args : `~lsst.afw.table.Catalog`
Additional catalogs to subset for the children to return.
Returns
-------
children : a single iterable of `~lsst.afw.table.SourceRecord`
Children sources if ``parent`` is of type `int`, or a generator
yielding a `~lsst.afw.table.SourceRecord`s Children sources for
each parent if ``parent`` is an `iterable`.
Raises
------
AssertionError
Raised if the catalog is not sorted by the parent key.
Notes
-----
Each call to this function checks if the catalog is sorted, which is
of O(n) complexity, while fetching the children is of O(log n). To
minimize the computational overhead, it is preferable to prepare an
iterable of parent ids for which the children need to be fetched and
pass the iterable as ``parent``.
Definition at line 35 of file _source.py.