diaCatalogSourceSelector.py

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# This file is part of ip_diffim.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (https://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
import numpy as np
 
from lsst.pipe.base import Struct
import lsst.pex.config as pexConfig
import lsst.afw.display as afwDisplay
import lsst.meas.algorithms as measAlg
 
__all__ = ["DiaCatalogSourceSelectorConfig", "DiaCatalogSourceSelectorTask"]
 
 
class DiaCatalogSourceSelectorConfig(measAlg.BaseStarSelectorConfig):
    # Selection cuts on the input source catalog
    fluxLim = pexConfig.Field(
        doc="specify the minimum psfFlux for good Kernel Candidates",
        dtype=float,
        default=0.0,
        check=lambda x: x >= 0.0,
    )
    fluxMax = pexConfig.Field(
        doc="specify the maximum psfFlux for good Kernel Candidates (ignored if == 0)",
        dtype=float,
        default=0.0,
        check=lambda x: x >= 0.0,
    )
    # Selection cuts on the reference catalog
    selectStar = pexConfig.Field(
        doc="Select objects that are flagged as stars",
        dtype=bool,
        default=True
    )
    selectGalaxy = pexConfig.Field(
        doc="Select objects that are flagged as galaxies",
        dtype=bool,
        default=False
    )
    includeVariable = pexConfig.Field(
        doc="Include objects that are known to be variable",
        dtype=bool,
        default=False
    )
    grMin = pexConfig.Field(
        doc="Minimum g-r color for selection (inclusive)",
        dtype=float,
        default=0.0
    )
    grMax = pexConfig.Field(
        doc="Maximum g-r color for selection (inclusive)",
        dtype=float,
        default=3.0
    )
 
    def setDefaults(self):
        measAlg.BaseStarSelectorConfig.setDefaults(self)
        self.badFlags = [
            "base_PixelFlags_flag_edge",
            "base_PixelFlags_flag_interpolatedCenter",
            "base_PixelFlags_flag_saturatedCenter",
            "slot_Centroid_flag",
        ]
 
 
class CheckSource(object):
    """A functor to check whether a source has any flags set that should cause it to be labeled bad."""
 
    def __init__(self, table, fluxLim, fluxMax, badFlags):
        self.keys = [table.getSchema().find(name).key for name in badFlags]
        self.fluxLim = fluxLim
        self.fluxMax = fluxMax
 
    def __call__(self, source):
        for k in self.keys:
            if source.get(k):
                return False
        if self.fluxLim is not None and source.getPsfInstFlux() < self.fluxLim:  # ignore faint objects
            return False
        if self.fluxMax != 0.0 and source.getPsfInstFlux() > self.fluxMax:  # ignore bright objects
            return False
        return True
 
 
@pexConfig.registerConfigurable("diaCatalog", measAlg.sourceSelectorRegistry)
class DiaCatalogSourceSelectorTask(measAlg.BaseSourceSelectorTask):
    """A task that selects sources for Kernel candidates.
 
    A naive star selector based on second moments. Use with caution.
 
    """
    ConfigClass = DiaCatalogSourceSelectorConfig
    usesMatches = True  # selectStars uses (requires) its matches argument
 
    def selectSources(self, sourceCat, matches=None, exposure=None):
        """Return a selection of sources for Kernel candidates.
 
        Parameters
        ----------
        sourceCat : `lsst.afw.table.SourceCatalog`
            Catalog of sources to select from.
            This catalog must be contiguous in memory.
        matches : `list` of `lsst.afw.table.ReferenceMatch`
             A match vector as produced by meas_astrom.
        exposure : `lsst.afw.image.Exposure` or None
            The exposure the catalog was built from; used for debug display.
 
        Returns
        -------
        struct : `lsst.pipe.base.Struct`
            The struct contains the following data:
 
            - selected : `array` of `bool``
                Boolean array of sources that were selected, same length as
                sourceCat.
        """
        import lsstDebug
        display = lsstDebug.Info(__name__).display
        displayExposure = lsstDebug.Info(__name__).displayExposure
        pauseAtEnd = lsstDebug.Info(__name__).pauseAtEnd
 
        if matches is None:
            raise RuntimeError("DiaCatalogSourceSelector requires matches")
 
        mi = exposure.getMaskedImage()
 
        if display and displayExposure:
            disp = afwDisplay.Display(frame=lsstDebug.frame)
            disp.mtv(mi, title="Kernel candidates")
        #
        # Look for flags in each Source
        #
        isGoodSource = CheckSource(sourceCat, self.config.fluxLim, self.config.fluxMax, self.config.badFlags)
 
        # Go through and find all the acceptable candidates in the catalogue
        selected = np.zeros(len(sourceCat), dtype=bool)
 
        if display and displayExposure:
            symbs = []
            ctypes = []
 
        doColorCut = True
 
        refSchema = matches[0][0].schema
        rRefFluxField = measAlg.getRefFluxField(refSchema, "r")
        gRefFluxField = measAlg.getRefFluxField(refSchema, "g")
        for i, (ref, source, d) in enumerate(matches):
            if not isGoodSource(source):
                if display and displayExposure:
                    symbs.append("+")
                    ctypes.append(afwDisplay.RED)
            else:
                isStar = not ref.get("resolved")
                isVar = not ref.get("photometric")
                gMag = None
                rMag = None
                if doColorCut:
                    try:
                        gMag = -2.5 * np.log10(ref.get(gRefFluxField))
                        rMag = -2.5 * np.log10(ref.get(rRefFluxField))
                    except KeyError:
                        self.log.warning("Cannot cut on color info; fields 'g' and 'r' do not exist")
                        doColorCut = False
                        isRightColor = True
                    else:
                        isRightColor = (gMag-rMag) >= self.config.grMin and (gMag-rMag) <= self.config.grMax
 
                isRightType = (self.config.selectStar and isStar) or (self.config.selectGalaxy and not isStar)
                isRightVar = (self.config.includeVariable) or (self.config.includeVariable is isVar)
                if isRightType and isRightVar and isRightColor:
                    selected[i] = True
                    if display and displayExposure:
                        symbs.append("+")
                        ctypes.append(afwDisplay.GREEN)
                elif display and displayExposure:
                    symbs.append("o")
                    ctypes.append(afwDisplay.BLUE)
 
        if display and displayExposure:
            disp = afwDisplay.Display(frame=lsstDebug.frame)
            with disp.Buffering():
                for (ref, source, d), symb, ctype in zip(matches, symbs, ctypes):
                    disp.dot(symb, source.getX() - mi.getX0(), source.getY() - mi.getY0(),
                             size=4, ctype=ctype)
 
        if display:
            lsstDebug.frame += 1
            if pauseAtEnd:
                input("Continue? y[es] p[db] ")
 
        return Struct(selected=selected)