Coverage for python/lsst/obs/base/exposureIdInfo.py: 35%

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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/>. 

21 

22from __future__ import annotations 

23 

24__all__ = ["ExposureIdInfo"] 

25 

26from typing import Optional 

27 

28from deprecated.sphinx import deprecated 

29from lsst.afw.table import IdFactory 

30from lsst.daf.butler import DataCoordinate 

31 

32 

33@deprecated( 

34 "Deprecated in favor of lsst.meas.base.CatalogIdPacker; will be removed after v27.", 

35 version="v26", 

36 category=FutureWarning, 

37) 

38class ExposureIdInfo: 

39 """Struct representing an exposure ID and the number of bits it uses. 

40 

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. 

58 

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``, 

63 

64 .. code-block:: python 

65 

66 from lsst.afw.table import SourceTable 

67 schema = SourceTable.makeMinimalSchema() 

68 #...add fields to schema as desired, then... 

69 sourceTable = SourceTable.make(self.schema, info.makeSourceIdFactory()) 

70 

71 An `ExposureIdInfo` instance can be obtained from a 

72 `~lsst.daf.butler.DataCoordinate` with: 

73 

74 .. code-block:: python 

75 

76 expandedDataId = butler.registry.expandDataId(dataId) 

77 info = ExposureIdInfo.fromDataId(expandedDataId, "visit_detector") 

78 

79 The first line should be unnecessary for the data IDs passed to 

80 `~lsst.pipe.base.PipelineTask` methods, as those are already expanded, and 

81 ``"visit_detector"`` can be replaced by other strings to pack data IDs with 

82 different dimensions (e.g. ``"tract_patch"`` or ``"tract_patch_band"``); 

83 see the data repository's dimensions configuration for other options. 

84 

85 At least one bit must be reserved for the exposure ID, even if there is no 

86 exposure ID, for reasons that are not entirely clear (this is DM-6664). 

87 """ 

88 

89 def __init__(self, expId: int = 0, expBits: int = 1, maxBits: Optional[int] = None): 

90 """Construct an ExposureIdInfo 

91 

92 See the class doc string for an explanation of the arguments. 

93 """ 

94 expId = int(expId) 

95 expBits = int(expBits) 

96 

97 if expId.bit_length() > expBits: 

98 raise RuntimeError("expId=%s uses %s bits > expBits=%s" % (expId, expId.bit_length(), expBits)) 

99 

100 self.expId = expId 

101 self.expBits = expBits 

102 

103 if maxBits is not None: 

104 maxBits = int(maxBits) 

105 if maxBits < expBits: 

106 raise RuntimeError("expBits=%s > maxBits=%s" % (expBits, maxBits)) 

107 self.maxBits = maxBits 

108 

109 def __repr__(self) -> str: 

110 return ( 

111 f"{self.__class__.__name__}(expId={self.expId}, expBits={self.expBits}, maxBits={self.maxBits})" 

112 ) 

113 

114 @classmethod 

115 def fromDataId( 

116 cls, dataId: DataCoordinate, name: str = "visit_detector", maxBits: Optional[int] = None 

117 ) -> ExposureIdInfo: 

118 """Construct an instance from a fully-expanded data ID. 

119 

120 Parameters 

121 ---------- 

122 dataId : `lsst.daf.butler.DataCoordinate` 

123 An expanded data ID that identifies the dimensions to be packed and 

124 contains extra information about the maximum values for those 

125 dimensions. An expanded data ID can be obtained from 

126 `Registry.expandDataId`, but all data IDs passed to `PipelineTask` 

127 methods should already be expanded. 

128 name : `str`, optional 

129 Name of the packer to use. The set of available packers can be 

130 found in the data repository's dimension configuration (see the 

131 "packers" section of ``dimensions.yaml`` in ``daf_butler`` for the 

132 defaults). 

133 maxBits : `int`, optional 

134 Forwarded as the ``__init__`` parameter of the same name. Should 

135 usually be unnecessary. 

136 

137 Returns 

138 ------- 

139 info : `ExposureIdInfo` 

140 An `ExposureIdInfo` instance. 

141 """ 

142 if not isinstance(dataId, DataCoordinate) or not dataId.hasRecords(): 

143 raise RuntimeError( 

144 "A fully-expanded data ID is required; use Registry.expandDataId to obtain one." 

145 ) 

146 expId, expBits = dataId.pack(name, returnMaxBits=True) 

147 return cls(expId=expId, expBits=expBits, maxBits=maxBits) 

148 

149 @property 

150 def unusedBits(self) -> int: 

151 """Maximum number of bits available for non-exposure info `(int)`.""" 

152 if self.maxBits is None: 

153 from lsst.afw.table import IdFactory 

154 

155 return IdFactory.computeReservedFromMaxBits(self.expBits) 

156 else: 

157 return self.maxBits - self.expBits 

158 

159 def makeSourceIdFactory(self) -> IdFactory: 

160 """Make a `lsst.afw.table.SourceTable.IdFactory` instance from this 

161 exposure information. 

162 

163 Returns 

164 ------- 

165 idFactory : `lsst.afw.table.SourceTable.IdFactory` 

166 An ID factory that generates new IDs that fold in the image IDs 

167 managed by this object. 

168 """ 

169 return IdFactory.makeSource(self.expId, self.unusedBits)