Coverage for python/lsst/pipe/tasks/colorterms.py : 90%

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1#
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
24import numpy as np
25import astropy.units as u
27from lsst.afw.image import abMagErrFromFluxErr
28import lsst.pex.exceptions as pexExcept
29from lsst.pex.config import Config, Field, ConfigDictField
30from lsst.afw.image import Filter
32__all__ = ["ColortermNotFoundError", "Colorterm", "ColortermDict", "ColortermLibrary"]
35class ColortermNotFoundError(LookupError):
36 """Exception class indicating we couldn't find a colorterm
37 """
38 pass
41class Colorterm(Config):
42 """!Colorterm correction for one pair of filters
44 The transformed magnitude p' is given by
45 p' = primary + c0 + c1*(primary - secondary) + c2*(primary - secondary)**2
47 To construct a Colorterm, use keyword arguments:
48 Colorterm(primary=primaryFilterName, secondary=secondaryFilterName, c0=c0value, c1=c1Coeff, c2=c2Coeff)
49 where c0-c2 are optional. For example (omitting c2):
50 Colorterm(primary="g", secondary="r", c0=-0.00816446, c1=-0.08366937)
52 This is subclass of Config. That is a bit of a hack to make it easy to store the data
53 in an appropriate obs_* package as a config override file. In the long term some other
54 means of persistence will be used, at which point the constructor can be simplified
55 to not require keyword arguments. (Fixing DM-2831 will also allow making a custom constructor).
56 """
57 primary = Field(dtype=str, doc="name of primary filter")
58 secondary = Field(dtype=str, doc="name of secondary filter")
59 c0 = Field(dtype=float, default=0.0, doc="Constant parameter")
60 c1 = Field(dtype=float, default=0.0, doc="First-order parameter")
61 c2 = Field(dtype=float, default=0.0, doc="Second-order parameter")
63 def getCorrectedMagnitudes(self, refCat, filterName):
64 """Return the colorterm corrected magnitudes for a given filter.
66 Parameters
67 ----------
68 refCat : `lsst.afw.table.SimpleCatalog`
69 The reference catalog to apply color corrections to.
70 filterName : `str`
71 The camera filter to correct the reference catalog into.
73 Returns
74 -------
75 RefMag : `np.ndarray`
76 The corrected AB magnitudes.
77 RefMagErr : `np.ndarray`
78 The corrected AB magnitude errors.
80 Raises
81 ------
82 KeyError
83 Raised if the reference catalog does not have a flux uncertainty
84 for that filter.
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 """
92 def getFluxes(fluxField):
93 """Get the flux and fluxErr of this field from refCat."""
94 fluxKey = refCat.schema.find(fluxField).key
95 refFlux = refCat[fluxKey]
96 try:
97 fluxErrKey = refCat.schema.find(fluxField + "Err").key
98 refFluxErr = refCat[fluxErrKey]
99 except KeyError as e:
100 raise KeyError("Reference catalog does not have flux uncertainties for %s" % fluxField) from e
102 return refFlux, refFluxErr
104 primaryFlux, primaryErr = getFluxes(self.primary + "_flux")
105 secondaryFlux, secondaryErr = getFluxes(self.secondary + "_flux")
107 primaryMag = u.Quantity(primaryFlux, u.nJy).to_value(u.ABmag)
108 secondaryMag = u.Quantity(secondaryFlux, u.nJy).to_value(u.ABmag)
110 refMag = self.transformMags(primaryMag, secondaryMag)
111 refFluxErrArr = self.propagateFluxErrors(primaryErr, secondaryErr)
113 # HACK convert to Jy until we have a replacement for this (DM-16903)
114 refMagErr = abMagErrFromFluxErr(refFluxErrArr*1e-9, primaryFlux*1e-9)
116 return refMag, refMagErr
118 def transformSource(self, source):
119 """!Transform the brightness of a source
121 @param[in] source source whose brightness is to be converted; must support get(filterName)
122 (e.g. source.get("r")) method, as do afw::table::Source and dicts.
123 @return the transformed source magnitude
124 """
125 return self.transformMags(source.get(self.primary), source.get(self.secondary))
127 def transformMags(self, primary, secondary):
128 """!Transform brightness
130 @param[in] primary brightness in primary filter (magnitude)
131 @param[in] secondary brightness in secondary filter (magnitude)
132 @return the transformed brightness (as a magnitude)
133 """
134 color = primary - secondary
135 return primary + self.c0 + color*(self.c1 + color*self.c2)
137 def propagateFluxErrors(self, primaryFluxErr, secondaryFluxErr):
138 return np.hypot((1 + self.c1)*primaryFluxErr, self.c1*secondaryFluxErr)
141class ColortermDict(Config):
142 """!A mapping of filterName to Colorterm
144 Different reference catalogs may need different ColortermDicts; see ColortermLibrary
146 To construct a ColortermDict use keyword arguments:
147 ColortermDict(data=dataDict)
148 where dataDict is a Python dict of filterName: Colorterm
149 For example:
150 ColortermDict(data={
151 'g': Colorterm(primary="g", secondary="r", c0=-0.00816446, c1=-0.08366937, c2=-0.00726883),
152 'r': Colorterm(primary="r", secondary="i", c0= 0.00231810, c1= 0.01284177, c2=-0.03068248),
153 'i': Colorterm(primary="i", secondary="z", c0= 0.00130204, c1=-0.16922042, c2=-0.01374245),
154 })
155 The constructor will likely be simplified at some point.
157 This is subclass of Config. That is a bit of a hack to make it easy to store the data
158 in an appropriate obs_* package as a config override file. In the long term some other
159 means of persistence will be used, at which point the constructor can be made saner.
160 """
161 data = ConfigDictField(
162 doc="Mapping of filter name to Colorterm",
163 keytype=str,
164 itemtype=Colorterm,
165 default={},
166 )
169class ColortermLibrary(Config):
170 """!A mapping of photometric reference catalog name or glob to ColortermDict
172 This allows photometric calibration using a variety of reference catalogs.
174 To construct a ColortermLibrary, use keyword arguments:
175 ColortermLibrary(data=dataDict)
176 where dataDict is a Python dict of catalog_name_or_glob: ColortermDict
178 For example:
179 ColortermLibrary(data = {
180 "hsc*": ColortermDict(data={
181 'g': Colorterm(primary="g", secondary="g"),
182 'r': Colorterm(primary="r", secondary="r"),
183 ...
184 }),
185 "sdss*": ColortermDict(data={
186 'g': Colorterm(primary="g", secondary="r", c0=-0.00816446, c1=-0.08366937, c2=-0.00726883),
187 'r': Colorterm(primary="r", secondary="i", c0= 0.00231810, c1= 0.01284177, c2=-0.03068248),
188 ...
189 }),
190 })
192 This is subclass of Config. That is a bit of a hack to make it easy to store the data
193 in an appropriate obs_* package as a config override file. In the long term some other
194 means of persistence will be used, at which point the constructor can be made saner.
195 """
196 data = ConfigDictField(
197 doc="Mapping of reference catalog name (or glob) to ColortermDict",
198 keytype=str,
199 itemtype=ColortermDict,
200 default={},
201 )
203 def getColorterm(self, filterName, photoCatName, doRaise=True):
204 """!Get the appropriate Colorterm from the library
206 Use dict of color terms in the library that matches the photoCatName.
207 If the photoCatName exactly matches an entry in the library, that
208 dict is used; otherwise if the photoCatName matches a single glob (shell syntax,
209 e.g., "sdss-*" will match "sdss-dr8"), then that is used. If there is no
210 exact match and no unique match to the globs, raise an exception.
212 @param filterName name of filter
213 @param photoCatName name of photometric reference catalog from which to retrieve the data.
214 This argument is not glob-expanded (but the catalog names in the library are,
215 if no exact match is found).
216 @param[in] doRaise if True then raise ColortermNotFoundError if no suitable Colorterm found;
217 if False then return a null Colorterm with filterName as the primary and secondary filter
218 @return the appropriate Colorterm
220 @throw ColortermNotFoundError if no suitable Colorterm found and doRaise true;
221 other exceptions may be raised for unexpected errors, regardless of the value of doRaise
222 """
223 try:
224 trueRefCatName = None
225 ctDictConfig = self.data.get(photoCatName)
226 if ctDictConfig is None: 226 ↛ 239line 226 didn't jump to line 239, because the condition on line 226 was never false
227 # try glob expression
228 matchList = [libRefNameGlob for libRefNameGlob in self.data
229 if fnmatch.fnmatch(photoCatName, libRefNameGlob)]
230 if len(matchList) == 1:
231 trueRefCatName = matchList[0]
232 ctDictConfig = self.data[trueRefCatName]
233 elif len(matchList) > 1: 233 ↛ 234line 233 didn't jump to line 234, because the condition on line 233 was never true
234 raise ColortermNotFoundError(
235 "Multiple library globs match photoCatName %r: %s" % (photoCatName, matchList))
236 else:
237 raise ColortermNotFoundError(
238 "No colorterm dict found with photoCatName %r" % photoCatName)
239 ctDict = ctDictConfig.data
240 if filterName not in ctDict:
241 # Perhaps it's an alias
242 try:
243 filterName = Filter(Filter(filterName).getId()).getName()
244 except pexExcept.NotFoundError:
245 pass # this will be handled shortly
246 if filterName not in ctDict: 246 ↛ 252line 246 didn't jump to line 252, because the condition on line 246 was never false
247 errMsg = "No colorterm found for filter %r with photoCatName %r" % (
248 filterName, photoCatName)
249 if trueRefCatName is not None: 249 ↛ 251line 249 didn't jump to line 251, because the condition on line 249 was never false
250 errMsg += " = catalog %r" % (trueRefCatName,)
251 raise ColortermNotFoundError(errMsg)
252 return ctDict[filterName]
253 except ColortermNotFoundError:
254 if doRaise: 254 ↛ 257line 254 didn't jump to line 257, because the condition on line 254 was never false
255 raise
256 else:
257 return Colorterm(filterName, filterName)