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# 

# LSST Data Management System 

# 

# Copyright 2008-2017 AURA/LSST. 

# 

# This product includes software developed by the 

# LSST Project (http://www.lsst.org/). 

# 

# 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 LSST License Statement and 

# the GNU General Public License along with this program. If not, 

# see <https://www.lsstcorp.org/LegalNotices/>. 

# 

 

import numpy as np 

 

import lsst.pex.config as pexConfig 

from .sourceSelector import BaseSourceSelectorConfig, BaseSourceSelectorTask, sourceSelectorRegistry 

from lsst.pipe.base import Struct 

 

 

class MatcherSourceSelectorConfig(BaseSourceSelectorConfig): 

sourceFluxType = pexConfig.Field( 

doc="Type of source flux; typically one of Ap or Psf", 

dtype=str, 

default="Ap", 

) 

minSnr = pexConfig.Field( 

dtype=float, 

doc="Minimum allowed signal-to-noise ratio for sources used for matching " 

"(in the flux specified by sourceFluxType); <= 0 for no limit", 

default=40, 

) 

excludePixelFlags = pexConfig.Field( 

dtype=bool, 

doc="Exclude objects that have saturated, interpolated, or edge " 

"pixels using PixelFlags. For matchOptimisticB set this to False " 

"to recover previous matcher selector behavior.", 

default=True, 

) 

 

 

@pexConfig.registerConfigurable("matcher", sourceSelectorRegistry) 

class MatcherSourceSelectorTask(BaseSourceSelectorTask): 

"""Select sources that are useful for matching. 

 

Good matching sources have high signal/noise, are non-blended. They need not 

be PSF sources, just have reliable centroids. 

 

Distinguished from astrometrySourceSelector because it is more lenient 

(i.e. not checking footprints or bad flags). 

""" 

ConfigClass = MatcherSourceSelectorConfig 

 

def __init__(self, *args, **kwargs): 

BaseSourceSelectorTask.__init__(self, *args, **kwargs) 

 

def selectSources(self, sourceCat, matches=None, exposure=None): 

"""Return a selection of sources that are useful for matching. 

 

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` or None 

Ignored in this SourceSelector. 

exposure : `lsst.afw.image.Exposure` or None 

The exposure the catalog was built from; used for debug display. 

 

Return 

------ 

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. 

""" 

self._getSchemaKeys(sourceCat.schema) 

 

good = self._isUsable(sourceCat) 

if self.config.excludePixelFlags: 

good = good & self._isGood(sourceCat) 

return Struct(selected=good) 

 

def _getSchemaKeys(self, schema): 

"""Extract and save the necessary keys from schema with asKey.""" 

self.parentKey = schema["parent"].asKey() 

self.centroidXKey = schema["slot_Centroid_x"].asKey() 

self.centroidYKey = schema["slot_Centroid_y"].asKey() 

self.centroidFlagKey = schema["slot_Centroid_flag"].asKey() 

 

fluxPrefix = "slot_%sFlux_" % (self.config.sourceFluxType,) 

self.fluxField = fluxPrefix + "instFlux" 

self.fluxKey = schema[fluxPrefix + "instFlux"].asKey() 

self.fluxFlagKey = schema[fluxPrefix + "flag"].asKey() 

self.fluxErrKey = schema[fluxPrefix + "instFluxErr"].asKey() 

 

self.edgeKey = schema["base_PixelFlags_flag_edge"].asKey() 

self.interpolatedCenterKey = schema["base_PixelFlags_flag_interpolatedCenter"].asKey() 

self.saturatedKey = schema["base_PixelFlags_flag_saturated"].asKey() 

 

def _isParent(self, sourceCat): 

"""Return True for each source that is the parent source.""" 

test = (sourceCat.get(self.parentKey) == 0) 

return test 

 

def _hasCentroid(self, sourceCat): 

"""Return True for each source that has a valid centroid""" 

return np.isfinite(sourceCat.get(self.centroidXKey)) \ 

& np.isfinite(sourceCat.get(self.centroidYKey)) \ 

& ~sourceCat.get(self.centroidFlagKey) 

 

def _goodSN(self, sourceCat): 

"""Return True for each source that has Signal/Noise > config.minSnr.""" 

if self.config.minSnr <= 0: 

return True 

else: 

with np.errstate(invalid="ignore"): # suppress NAN warnings 

return sourceCat.get(self.fluxKey)/sourceCat.get(self.fluxErrKey) > self.config.minSnr 

 

def _isUsable(self, sourceCat): 

""" 

Return True for each source that is usable for matching, even if it may 

have a poor centroid. 

 

For a source to be usable it must: 

- have a valid centroid 

- not be deblended 

- have a valid instFlux (of the type specified in this object's constructor) 

- have adequate signal-to-noise 

""" 

return self._hasCentroid(sourceCat) \ 

& self._isParent(sourceCat) \ 

& self._goodSN(sourceCat) \ 

& ~sourceCat.get(self.fluxFlagKey) 

 

def _isGood(self, sourceCat): 

""" 

Return True for each source that is usable for matching, even if it may 

have a poor centroid. 

 

For a source to be usable it must: 

- Not be on a CCD edge. 

- Not have an interpolated pixel within 3x3 around their centroid. 

- Not have a saturated pixel in their footprint. 

""" 

return ~sourceCat.get(self.edgeKey) & \ 

~sourceCat.get(self.interpolatedCenterKey) & \ 

~sourceCat.get(self.saturatedKey)