25 from ._base
import Catalog
26 from ._table
import SourceCatalog, SourceTable
28 Catalog.register(
"Source", SourceCatalog)
35 """Return the subset of self for which the parent field equals the
38 In order for this method to return the correct result, it must be
39 sorted by parent (i.e. self.isSorted(SourceTable.getParentKey()) must
40 be True). This is naturally the case with SourceCatalogs produced by
41 the detection and deblending tasks, but it may not be true when
42 concatenating multiple such catalogs.
44 Additional Catalogs or sequences whose elements correspond in order to
45 the records of self (i.e. ``zip(self, *args)`` is valid) will be
46 subset using the same slice object used on self, and these subsets
47 will be returned along with the subset of self.
51 parent : `int` or `iterable` of `int`
52 ID(s) of the parent(s) to get children for.
53 args : `~lsst.afw.table.Catalog`
54 Additional catalogs to subset for the children to return.
58 children : a single iterable of `~lsst.afw.table.SourceRecord`
59 Children sources if ``parent`` is of type `int`, or a generator
60 yielding a `~lsst.afw.table.SourceRecord`s Children sources for
61 each parent if ``parent`` is an `iterable`.
66 Raised if the catalog is not sorted by the parent key.
70 Each call to this function checks if the catalog is sorted, which is
71 of O(n) complexity, while fetching the children is of O(log n). To
72 minimize the computational overhead, it is preferable to prepare an
73 iterable of parent ids for which the children need to be fetched and
74 pass the iterable as ``parent``.
76 if not self.isSorted(SourceTable.getParentKey()):
78 "The table is not sorted by parent, so cannot getChildren")
80 def _getChildrenWithoutChecking(parent):
81 """Return the subset of self for which the parent field equals the
84 This function works as desired only if `self` is sorted by the
85 parent key, but does not check if it is sorted. This function must
86 be used only after ensuring outside of the function that
87 self.isSorted(SourceTable.getParentKey() evaluates to True.
92 ID of the parent to get children for.
96 children : iterable of `~lsst.afw.table.SourceRecord`
99 s = self.equal_range(parent, SourceTable.getParentKey())
101 return (self[s],) + tuple(arg[s]
for arg
in args)
106 return (_getChildrenWithoutChecking(p)
for p
in parent)
108 return _getChildrenWithoutChecking(parent)
def getChildren(self, parent, *args)