flaggedSourceSelector.py

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# This file is part of meas_algorithms.
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"""Select sources that have an existing flag field set."""
import lsst.pex.config
import lsst.afw.table
import lsst.pipe.base as pipeBase
 
from .sourceSelector import BaseSourceSelectorTask, sourceSelectorRegistry
 
__all__ = ["FlaggedSourceSelectorConfig", "FlaggedSourceSelectorTask"]
 
 
class FlaggedSourceSelectorConfig(BaseSourceSelectorTask.ConfigClass):
    field = lsst.pex.config.Field(
        dtype=str, default="calib_psf_used",
        doc="Name of a flag field that is True for Sources that should be used.",
    )
 
 
@lsst.pex.config.registerConfigurable("flagged", sourceSelectorRegistry)
class FlaggedSourceSelectorTask(BaseSourceSelectorTask):
    """
    A trivial SourceSelector that simply uses an existing flag field to filter
    a SourceCatalog.
 
    This is most frequently used in steps that occur after the a PSF model has
    been built, to allow other procedures that need Sources to use the set of
    Sources used to determine the PSF.
 
    Attributes
    ----------
    usesMatches : `bool`
        A boolean variable specify if the inherited source selector uses
        matches.
    """
 
    ConfigClass = FlaggedSourceSelectorConfig
    _DefaultName = "flagged"
 
    def selectSources(self, sourceCat, matches=None, exposure=None):
        """Return a bool array representing which sources to select from
        sourceCat.
 
        The input catalog must be contiguous in memory.
 
        Parameters
        ----------
        sourceCat : `lsst.afw.table.SourceCatalog`
            Catalog of sources to select from.
        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.
 
        Returns
        -------
        struct : `lsst.pipe.base.Struct`
            The struct contains the following data:
 
            ``selected``
                Boolean array of sources that were selected, same length as
                ``sourceCat``. (`numpy.ndarray` of `bool`)
        """
        key = sourceCat.schema.find(self.config.field).key
        return pipeBase.Struct(selected=sourceCat[key])