lsst.pipe.tasks g260ff8ed1d+3fe987bc49
colorterms.py
Go to the documentation of this file.
2# LSST Data Management System
3# Copyright 2008, 2009, 2010, 2011 LSST Corporation.
4#
5# This product includes software developed by the
6# LSST Project (http://www.lsst.org/).
7#
8# This program is free software: you can redistribute it and/or modify
9# it under the terms of the GNU General Public License as published by
10# the Free Software Foundation, either version 3 of the License, or
11# (at your option) any later version.
12#
13# This program is distributed in the hope that it will be useful,
14# but WITHOUT ANY WARRANTY; without even the implied warranty of
15# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16# GNU General Public License for more details.
17#
18# You should have received a copy of the LSST License Statement and
19# the GNU General Public License along with this program. If not,
20# see <http://www.lsstcorp.org/LegalNotices/>.
21#
22import fnmatch
23import warnings
24
25import numpy as np
26import astropy.units as u
27
28from lsst.afw.image import abMagErrFromFluxErr
29from lsst.pex.config import Config, Field, ConfigDictField
30
31__all__ = ["ColortermNotFoundError", "Colorterm", "ColortermDict", "ColortermLibrary"]
32
33
34class ColortermNotFoundError(LookupError):
35 """Exception class indicating we couldn't find a colorterm
36 """
37 pass
38
39
40class Colorterm(Config):
41 """!Colorterm correction for one pair of filters
42
43 The transformed magnitude p' is given by
44 p' = primary + c0 + c1*(primary - secondary) + c2*(primary - secondary)**2
45
46 To construct a Colorterm, use keyword arguments:
47 Colorterm(primary=primaryFilterName, secondary=secondaryFilterName, c0=c0value, c1=c1Coeff, c2=c2Coeff)
48 where c0-c2 are optional. For example (omitting c2):
49 Colorterm(primary="g", secondary="r", c0=-0.00816446, c1=-0.08366937)
50
51 This is subclass of Config. That is a bit of a hack to make it easy to store the data
52 in an appropriate obs_* package as a config override file. In the long term some other
53 means of persistence will be used, at which point the constructor can be simplified
54 to not require keyword arguments. (Fixing DM-2831 will also allow making a custom constructor).
55 """
56 primary = Field(dtype=str, doc="name of primary filter")
57 secondary = Field(dtype=str, doc="name of secondary filter")
58 c0 = Field(dtype=float, default=0.0, doc="Constant parameter")
59 c1 = Field(dtype=float, default=0.0, doc="First-order parameter")
60 c2 = Field(dtype=float, default=0.0, doc="Second-order parameter")
61
62 def getCorrectedMagnitudes(self, refCat, filterName="deprecatedArgument"):
63 """Return the colorterm corrected magnitudes for a given filter.
64
65 Parameters
66 ----------
68 The reference catalog to apply color corrections to.
69 filterName : `str`, deprecated
70 The camera filter to correct the reference catalog into.
71 The ``filterName`` argument is unused and will be removed in v23.
72
73 Returns
74 -------
75 RefMag : `np.ndarray`
76 The corrected AB magnitudes.
77 RefMagErr : `np.ndarray`
78 The corrected AB magnitude errors.
79
80 Raises
81 ------
82 KeyError
83 Raised if the reference catalog does not have a flux uncertainty
84 for that filter.
85
86 Notes
87 -----
88 WARNING: I do not know that we can trust the propagation of magnitude
89 errors returned by this method. They need more thorough tests.
90 """
91
92 if filterName != "deprecatedArgument":
93 msg = "Colorterm.getCorrectedMagnitudes() `filterName` arg is unused and will be removed in v23."
94 warnings.warn(msg, category=FutureWarning)
95
96 def getFluxes(fluxField):
97 """Get the flux and fluxErr of this field from refCat."""
98 fluxKey = refCat.schema.find(fluxField).key
99 refFlux = refCat[fluxKey]
100 try:
101 fluxErrKey = refCat.schema.find(fluxField + "Err").key
102 refFluxErr = refCat[fluxErrKey]
103 except KeyError as e:
104 raise KeyError("Reference catalog does not have flux uncertainties for %s" % fluxField) from e
105
106 return refFlux, refFluxErr
107
108 primaryFlux, primaryErr = getFluxes(self.primaryprimary + "_flux")
109 secondaryFlux, secondaryErr = getFluxes(self.secondarysecondary + "_flux")
110
111 primaryMag = u.Quantity(primaryFlux, u.nJy).to_value(u.ABmag)
112 secondaryMag = u.Quantity(secondaryFlux, u.nJy).to_value(u.ABmag)
113
114 refMag = self.transformMagstransformMags(primaryMag, secondaryMag)
115 refFluxErrArr = self.propagateFluxErrorspropagateFluxErrors(primaryErr, secondaryErr)
116
117 # HACK convert to Jy until we have a replacement for this (DM-16903)
118 refMagErr = abMagErrFromFluxErr(refFluxErrArr*1e-9, primaryFlux*1e-9)
119
120 return refMag, refMagErr
121
122 def transformSource(self, source):
123 """!Transform the brightness of a source
124
125 @param[in] source source whose brightness is to be converted; must support get(filterName)
126 (e.g. source.get("r")) method, as do afw::table::Source and dicts.
127 @return the transformed source magnitude
128 """
129 return self.transformMagstransformMags(source.get(self.primaryprimary), source.get(self.secondarysecondary))
130
131 def transformMags(self, primary, secondary):
132 """!Transform brightness
133
134 @param[in] primary brightness in primary filter (magnitude)
135 @param[in] secondary brightness in secondary filter (magnitude)
136 @return the transformed brightness (as a magnitude)
137 """
138 color = primary - secondary
139 return primary + self.c0c0 + color*(self.c1c1 + color*self.c2c2)
140
141 def propagateFluxErrors(self, primaryFluxErr, secondaryFluxErr):
142 return np.hypot((1 + self.c1c1)*primaryFluxErr, self.c1c1*secondaryFluxErr)
143
144
145class ColortermDict(Config):
146 """A mapping of physical filter label to Colorterm
147
148 Different reference catalogs may need different ColortermDicts; see ColortermLibrary
149
150 To construct a ColortermDict use keyword arguments:
151 ColortermDict(data=dataDict)
152 where dataDict is a Python dict of filterName: Colorterm
153 For example:
154 ColortermDict(data={
155 'g': Colorterm(primary="g", secondary="r", c0=-0.00816446, c1=-0.08366937, c2=-0.00726883),
156 'r': Colorterm(primary="r", secondary="i", c0= 0.00231810, c1= 0.01284177, c2=-0.03068248),
157 'i': Colorterm(primary="i", secondary="z", c0= 0.00130204, c1=-0.16922042, c2=-0.01374245),
158 })
159 The constructor will likely be simplified at some point.
160
161 This is subclass of Config. That is a bit of a hack to make it easy to store the data
162 in an appropriate obs_* package as a config override file. In the long term some other
163 means of persistence will be used, at which point the constructor can be made saner.
164 """
165 data = ConfigDictField(
166 doc="Mapping of filter name to Colorterm",
167 keytype=str,
168 itemtype=Colorterm,
169 default={},
170 )
171
172
173class ColortermLibrary(Config):
174 """!A mapping of photometric reference catalog name or glob to ColortermDict
175
176 This allows photometric calibration using a variety of reference catalogs.
177
178 To construct a ColortermLibrary, use keyword arguments:
179 ColortermLibrary(data=dataDict)
180 where dataDict is a Python dict of catalog_name_or_glob: ColortermDict
181
182 For example:
183 ColortermLibrary(data = {
184 "hsc*": ColortermDict(data={
185 'g': Colorterm(primary="g", secondary="g"),
186 'r': Colorterm(primary="r", secondary="r"),
187 ...
188 }),
189 "sdss*": ColortermDict(data={
190 'g': Colorterm(primary="g", secondary="r", c0=-0.00816446, c1=-0.08366937, c2=-0.00726883),
191 'r': Colorterm(primary="r", secondary="i", c0= 0.00231810, c1= 0.01284177, c2=-0.03068248),
192 ...
193 }),
194 })
195
196 This is subclass of Config. That is a bit of a hack to make it easy to store the data
197 in an appropriate obs_* package as a config override file. In the long term some other
198 means of persistence will be used, at which point the constructor can be made saner.
199 """
200 data = ConfigDictField(
201 doc="Mapping of reference catalog name (or glob) to ColortermDict",
202 keytype=str,
203 itemtype=ColortermDict,
204 default={},
205 )
206
207 def getColorterm(self, physicalFilter, photoCatName, doRaise=True):
208 """!Get the appropriate Colorterm from the library
209
210 Use dict of color terms in the library that matches the photoCatName.
211 If the photoCatName exactly matches an entry in the library, that
212 dict is used; otherwise if the photoCatName matches a single glob (shell syntax,
213 e.g., "sdss-*" will match "sdss-dr8"), then that is used. If there is no
214 exact match and no unique match to the globs, raise an exception.
215
216 @param physicalFilter Label of physical filter to correct to.
217 @param photoCatName name of photometric reference catalog from which to retrieve the data.
218 This argument is not glob-expanded (but the catalog names in the library are,
219 if no exact match is found).
220 @param[in] doRaise if True then raise ColortermNotFoundError if no suitable Colorterm found;
221 if False then return a null Colorterm with physicalFilter as the primary and secondary filter
222 @return the appropriate Colorterm
223
224 @throw ColortermNotFoundError if no suitable Colorterm found and doRaise true;
225 other exceptions may be raised for unexpected errors, regardless of the value of doRaise
226 """
227 try:
228 trueRefCatName = None
229 ctDictConfig = self.datadata.get(photoCatName)
230 if ctDictConfig is None:
231 # try glob expression
232 matchList = [libRefNameGlob for libRefNameGlob in self.datadata
233 if fnmatch.fnmatch(photoCatName, libRefNameGlob)]
234 if len(matchList) == 1:
235 trueRefCatName = matchList[0]
236 ctDictConfig = self.datadata[trueRefCatName]
237 elif len(matchList) > 1:
239 "Multiple library globs match photoCatName %r: %s" % (photoCatName, matchList))
240 else:
242 "No colorterm dict found with photoCatName %r" % photoCatName)
243 ctDict = ctDictConfig.data
244 if physicalFilter not in ctDict:
245 errMsg = "No colorterm found for filter %r with photoCatName %r" % (
246 physicalFilter, photoCatName)
247 if trueRefCatName is not None:
248 errMsg += " = catalog %r" % (trueRefCatName,)
249 raise ColortermNotFoundError(errMsg)
250 return ctDict[physicalFilter]
251 except ColortermNotFoundError:
252 if doRaise:
253 raise
254 else:
255 return Colorterm(physicalFilter, physicalFilter)
Colorterm correction for one pair of filters.
Definition: colorterms.py:40
def propagateFluxErrors(self, primaryFluxErr, secondaryFluxErr)
Definition: colorterms.py:141
def transformMags(self, primary, secondary)
Transform brightness.
Definition: colorterms.py:131
def getCorrectedMagnitudes(self, refCat, filterName="deprecatedArgument")
Definition: colorterms.py:62
def transformSource(self, source)
Transform the brightness of a source.
Definition: colorterms.py:122
A mapping of photometric reference catalog name or glob to ColortermDict.
Definition: colorterms.py:173
def getColorterm(self, physicalFilter, photoCatName, doRaise=True)
Get the appropriate Colorterm from the library.
Definition: colorterms.py:207