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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, 

) 

 

 

@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) 

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 + "flux" 

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

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

self.fluxErrKey = schema[fluxPrefix + "fluxErr"].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 flux (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) 

 

 

@pexConfig.registerConfigurable("matcherPessimistic", sourceSelectorRegistry) 

class MatcherPessimisticSourceSelectorTask(MatcherSourceSelectorTask): 

"""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. This inherited class adds 

the removal of saturated, interpolated, and edge_key objects to the set of 

bad flags. It is a temporary addition designed preserve the source selction 

used in matchOptimisticB. Once matchPessimisticB is adopted as the default 

source selector the class will be removed and the saturated, interpoalted, and 

edge_key flags will be added to the matcherSourceSelector class. 

 

TODO: Once DM-10399 is complete an RFC will be filed to make matchPessimisticB 

the default matcher this class will replace matcherSourceSelector with this source 

selector resulting in only one matcherSourceSeletor. The ticket describing 

this work is DM-10800. 

""" 

def _getSchemaKeys(self, schema): 

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

MatcherSourceSelectorTask._getSchemaKeys(self, schema) 

 

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 _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 flux (of the type specified in this object's constructor) 

- have adequate signal-to-noise 

""" 

result = MatcherSourceSelectorTask._isUsable(self, sourceCat) 

 

return result \ 

& ~sourceCat.get(self.edgeKey) \ 

& ~sourceCat.get(self.interpolatedCenterKey) \ 

& ~sourceCat.get(self.saturatedKey)