Coverage for python/lsst/obs/base/filters.py : 38%

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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/>.
22"""Classes to allow obs packages to define the filters used by an Instrument
23and for use by `lsst.afw.image.Filter`, gen2 dataIds, and gen3 Dimensions.
24"""
26__all__ = ("FilterDefinition", "FilterDefinitionCollection")
28import dataclasses
29import collections.abc
31import numpy as np
33import lsst.afw.image.utils
36class FilterDefinitionCollection(collections.abc.Sequence):
37 """An order-preserving collection of `FilterDefinition`s.
39 Parameters
40 ----------
41 filters : sequence
42 The filters in this collection.
43 """
45 _defined = None
46 """Whether these filters have been defined via
47 `~lsst.afw.image.utils.defineFilter`. If so, set to ``self`` to identify
48 the filter collection that defined them.
49 """
51 def __init__(self, *filters):
52 self._filters = list(filters)
54 def __getitem__(self, key):
55 return self._filters[key]
57 def __len__(self):
58 return len(self._filters)
60 def __str__(self):
61 return "FilterDefinitions(" + ', '.join(str(f) for f in self._filters) + ')'
63 def defineFilters(self):
64 """Define all the filters to `lsst.afw.image.Filter`.
66 `~lsst.afw.image.Filter` objects are singletons, so we protect against
67 filters being defined multiple times.
69 Raises
70 ------
71 RuntimeError
72 Raised if any other `FilterDefinitionCollection` has already called
73 ``defineFilters``.
74 """
75 if self._defined is None: 75 ↛ 80line 75 didn't jump to line 80, because the condition on line 75 was never false
76 self.reset()
77 for filter in self._filters: 77 ↛ 78line 77 didn't jump to line 78, because the loop on line 77 never started
78 filter.defineFilter()
79 FilterDefinitionCollection._defined = self
80 elif self._defined is self:
81 # noop: we've already defined these filters, so do nothing
82 pass
83 else:
84 msg = f"afw Filters were already defined on: {self._defined}"
85 raise RuntimeError(msg)
87 @classmethod
88 def reset(cls):
89 """Reset the afw Filter definitions and clear the `defined` singleton.
90 Use this in unittests that define different filters.
91 """
92 lsst.afw.image.utils.resetFilters()
93 cls._defined = None
96@dataclasses.dataclass(frozen=True)
97class FilterDefinition:
98 """The definition of an instrument's filter bandpass.
100 This class is used to interface between the `~lsst.afw.image.Filter` class
101 and the Gen2 `~lsst.daf.persistence.CameraMapper` and Gen3
102 `~lsst.obs.base.Instruments` and ``physical_filter``/``abstract_filter``
103 `~lsst.daf.butler.Dimension`.
105 This class is likely temporary, until we have a better versioned filter
106 definition system that includes complete transmission information.
107 """
109 physical_filter: str
110 """The name of a filter associated with a particular instrument: unique for
111 each piece of glass. This should match the exact filter name used in the
112 observatory's metadata.
114 This name is used to define the ``physical_filter`` gen3 Butler Dimension.
116 If neither ``abstract_filter`` or ``afw_name`` is defined, this is used
117 as the `~lsst.afw.image.Filter` ``name``, otherwise it is added to the
118 list of `~lsst.afw.image.Filter` aliases.
119 """
121 lambdaEff: float
122 """The effective wavelength of this filter (nm)."""
124 abstract_filter: str = None
125 """The generic name of a filter not associated with a particular instrument
126 (e.g. `r` for the SDSS Gunn r-band, which could be on SDSS, LSST, or HSC).
128 Not all filters have an abstract filter: engineering or test filters may
129 not have a genericly-termed filter name.
131 If specified and if `afw_name` is None, this is used as the
132 `~lsst.afw.image.Filter` ``name`` field, otherwise it is added to the list
133 of `~lsst.afw.image.Filter` aliases.
134 """
136 afw_name: str = None
137 """If not None, the name of the `~lsst.afw.image.Filter` object.
139 This is distinct from physical_filter and abstract_filter to maintain
140 backwards compatibility in some obs packages.
141 For example, for HSC there are two distinct ``r`` and ``i`` filters, named
142 ``r/r2`` and ``i/i2``.
143 """
145 lambdaMin: float = np.nan
146 """The minimum wavelength of this filter (nm; defined as 1% throughput)"""
147 lambdaMax: float = np.nan
148 """The maximum wavelength of this filter (nm; defined as 1% throughput)"""
150 alias: set = frozenset()
151 """Alternate names for this filter. These are added to the
152 `~lsst.afw.image.Filter` alias list.
153 """
155 def __post_init__(self):
156 # force alias to be immutable, so that hashing works
157 if not isinstance(self.alias, frozenset):
158 object.__setattr__(self, 'alias', frozenset(self.alias))
160 def __str__(self):
161 txt = f"FilterDefinition(physical_filter='{self.physical_filter}', lambdaEff='{self.lambdaEff}'"
162 if self.abstract_filter is not None:
163 txt += f", abstract_filter='{self.abstract_filter}'"
164 if self.afw_name is not None:
165 txt += f", afw_name='{self.afw_name}'"
166 if not np.isnan(self.lambdaMin):
167 txt += f", lambdaMin='{self.lambdaMin}'"
168 if not np.isnan(self.lambdaMax):
169 txt += f", lambdaMax='{self.lambdaMax}'"
170 if len(self.alias) != 0:
171 txt += f", alias='{self.alias}'"
172 return txt + ")"
174 def defineFilter(self):
175 """Declare the filters via afw.image.Filter.
176 """
177 aliases = set(self.alias)
178 name = self.physical_filter
179 if self.abstract_filter is not None:
180 name = self.abstract_filter
181 aliases.add(self.physical_filter)
182 if self.afw_name is not None:
183 name = self.afw_name
184 aliases.add(self.physical_filter)
185 # Only add `physical_filter/abstract_filter` as an alias if afw_name is defined.ee
186 if self.afw_name is not None:
187 if self.abstract_filter is not None:
188 aliases.add(self.abstract_filter)
189 lsst.afw.image.utils.defineFilter(name,
190 lambdaEff=self.lambdaEff,
191 lambdaMin=self.lambdaMin,
192 lambdaMax=self.lambdaMax,
193 alias=sorted(aliases))