Coverage for python/lsst/obs/base/exposureIdInfo.py: 39%
35 statements
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« prev ^ index » next coverage.py v7.3.2, created at 2023-12-03 10:45 +0000
1# This file is part of obs_base.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (https://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <https://www.gnu.org/licenses/>.
22from __future__ import annotations
24__all__ = ["ExposureIdInfo"]
27from deprecated.sphinx import deprecated
28from lsst.afw.table import IdFactory
29from lsst.daf.butler import DataCoordinate
32# TODO: remove on DM-38687.
33@deprecated(
34 "Deprecated in favor of `lsst.meas.base.IdGenerator`; will be removed after v26.",
35 version="v26",
36 category=FutureWarning,
37)
38class ExposureIdInfo:
39 """Struct representing an exposure ID and the number of bits it uses.
41 Parameters
42 ----------
43 expId : `int`
44 Exposure ID. Note that this is typically the ID of an
45 `afw.image.Exposure`, not the ID of an actual observation, and hence it
46 usually either includes a detector component or is derived from SkyMap
47 IDs, and the observation ID component usually represents a ``visit``
48 rather than ``exposure``. For code using the Gen3 butler, this will
49 usually be obtained via a `~lsst.daf.butler.DimensionPacker` (see
50 example below).
51 expBits : `int`
52 Maximum number of bits allowed for exposure IDs of this type.
53 maxBits : `int`, optional
54 Maximum number of bits available for values that combine exposure ID
55 with other information, such as source ID. If not provided
56 (recommended when possible), `unusedBits` will be computed by assuming
57 the full ID must fit an an `lsst.afw.table` RecordId field.
59 Examples
60 --------
61 One common use is creating an ID factory for making a source table.
62 For example, given a `ExposureIdInfo` instance ``info``,
64 .. code-block:: python
66 from lsst.afw.table import SourceTable
68 schema = SourceTable.makeMinimalSchema()
69 # ...add fields to schema as desired, then...
70 sourceTable = SourceTable.make(self.schema, info.makeSourceIdFactory())
72 An `ExposureIdInfo` instance can be obtained from a
73 `~lsst.daf.butler.DataCoordinate` with:
75 .. code-block:: python
77 expandedDataId = butler.registry.expandDataId(dataId)
78 info = ExposureIdInfo.fromDataId(expandedDataId, "visit_detector")
80 The first line should be unnecessary for the data IDs passed to
81 `~lsst.pipe.base.PipelineTask` methods, as those are already expanded, and
82 ``"visit_detector"`` can be replaced by other strings to pack data IDs with
83 different dimensions (e.g. ``"tract_patch"`` or ``"tract_patch_band"``);
84 see the data repository's dimensions configuration for other options.
86 At least one bit must be reserved for the exposure ID, even if there is no
87 exposure ID, for reasons that are not entirely clear (this is DM-6664).
88 """
90 def __init__(self, expId: int = 0, expBits: int = 1, maxBits: int | None = None):
91 """Construct an ExposureIdInfo.
93 See the class doc string for an explanation of the arguments.
94 """
95 expId = int(expId)
96 expBits = int(expBits)
98 if expId.bit_length() > expBits:
99 raise RuntimeError(f"expId={expId} uses {expId.bit_length()} bits > expBits={expBits}")
101 self.expId = expId
102 self.expBits = expBits
104 if maxBits is not None:
105 maxBits = int(maxBits)
106 if maxBits < expBits:
107 raise RuntimeError(f"expBits={expBits} > maxBits={maxBits}")
108 self.maxBits = maxBits
110 def __repr__(self) -> str:
111 return (
112 f"{self.__class__.__name__}(expId={self.expId}, expBits={self.expBits}, maxBits={self.maxBits})"
113 )
115 @classmethod
116 def fromDataId(
117 cls, dataId: DataCoordinate, name: str = "visit_detector", maxBits: int | None = None
118 ) -> ExposureIdInfo:
119 """Construct an instance from a fully-expanded data ID.
121 Parameters
122 ----------
123 dataId : `lsst.daf.butler.DataCoordinate`
124 An expanded data ID that identifies the dimensions to be packed and
125 contains extra information about the maximum values for those
126 dimensions. An expanded data ID can be obtained from
127 `Registry.expandDataId`, but all data IDs passed to `PipelineTask`
128 methods should already be expanded.
129 name : `str`, optional
130 Name of the packer to use. The set of available packers can be
131 found in the data repository's dimension configuration (see the
132 "packers" section of ``dimensions.yaml`` in ``daf_butler`` for the
133 defaults).
134 maxBits : `int`, optional
135 Forwarded as the ``__init__`` parameter of the same name. Should
136 usually be unnecessary.
138 Returns
139 -------
140 info : `ExposureIdInfo`
141 An `ExposureIdInfo` instance.
142 """
143 if not isinstance(dataId, DataCoordinate) or not dataId.hasRecords():
144 raise RuntimeError(
145 "A fully-expanded data ID is required; use Registry.expandDataId to obtain one."
146 )
147 expId, expBits = dataId.pack(name, returnMaxBits=True)
148 return cls(expId=expId, expBits=expBits, maxBits=maxBits)
150 @property
151 def unusedBits(self) -> int:
152 """Maximum number of bits available for non-exposure info `(int)`."""
153 if self.maxBits is None:
154 from lsst.afw.table import IdFactory
156 return IdFactory.computeReservedFromMaxBits(self.expBits)
157 else:
158 return self.maxBits - self.expBits
160 def makeSourceIdFactory(self) -> IdFactory:
161 """Make a `lsst.afw.table.SourceTable.IdFactory` instance from this
162 exposure information.
164 Returns
165 -------
166 idFactory : `lsst.afw.table.SourceTable.IdFactory`
167 An ID factory that generates new IDs that fold in the image IDs
168 managed by this object.
169 """
170 return IdFactory.makeSource(self.expId, self.unusedBits)