measurementInvestigationLib.py

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# This file is part of meas_base.
#
# 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
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# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
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# GNU General Public License for more details.
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from collections import Iterable

from lsst.afw.table import Schema, SourceCatalog
from lsst.meas.base import NoiseReplacer, NoiseReplacerConfig
from lsst.meas.base import SingleFrameMeasurementTask as SFMT  # noqa N814


def rebuildNoiseReplacer(exposure, measCat):
    """Recreate the `NoiseReplacer` used in measurement.

    Given a measurement catalog and the exposure on which the measurements
    were made, reconstruct the `NoiseReplacer` object that was used to mask
    out sources during measurement.

    Parameters
    ----------
    exposure : `lsst.afw.exposure.Exposure`
        The image on which measurements were made.

    measCat : `lsst.afw.table.SourceCatalog`
        Catalog containing the results measurements on each source.

    Returns
    -------
    noiseReplacer : `NoiseReplacer`
        Object used to replace and/or restore sources in the exposure with
        deterministic noise.
    """

    algMetadata = measCat.getMetadata()
    noiseReplacerConf = NoiseReplacerConfig()
    noiseReplacerConf.noiseSeedMultiplier = \
        algMetadata.getScalar(SFMT.NOISE_SEED_MULTIPLIER)
    noiseReplacerConf.noiseSource = algMetadata.getScalar(SFMT.NOISE_SOURCE)
    noiseReplacerConf.noiseOffset = algMetadata.getScalar(SFMT.NOISE_OFFSET)

    footprints = {src.getId(): (src.getParent(), src.getFootprint())
                  for src in measCat}

    try:
        exposureId = algMetadata.getScalar(SFMT.NOISE_EXPOSURE_ID)
    except Exception:
        exposureId = None

    noiseReplacer = NoiseReplacer(noiseReplacerConf, exposure, footprints,
                                  exposureId=exposureId)
    return noiseReplacer


def makeRerunCatalog(schema, oldCatalog, idList, fields=None,
                     resetParents=True, addParents=False):
    """Create a catalog prepopulated with IDs.

    This function is used to generate a `~lsst.afw.table.SourceCatalog`
    containing blank records with IDs as specified in the ``idList``
    parameter.

    This function is primarily used when re-running measurements on a
    particular footprint. Specifying IDs in the new measurement catalog which
    correspond to IDs in the old catalog makes comparing results much easier.

    The ``resetParents`` and ``addParents`` options are needed because
    `SingleFrameMeasurementTask.runPlugins` will skip child
    objects whose parents are not in the catalog.

    Parameters
    ----------
    schema : `lsst.afw.table.Schema`
        Schema used to describe the fields in the resulting catalog.

    oldCatalog : `lsst.afw.table.SourceCatalog`
        Catalog containing previous measurements.

    idList : iterable of `int`
        Iterable whose values should be numbers corresponding to measurement
        IDs which exist in ``oldCatalog``.

    fields : iterable of `str`
        Iterable whose entries should be strings corresponding to schema keys
        that exist in both the old catalog and input schema. Fields listed
        will be copied from the old catalog into the new catalog.

    resetParents : `bool`
        If `True`, child objects whose parents are not in the ``idList``
        will have their parents reset to zero.

    addParents : `bool`
        If `True`, parents of child objects will be added to ``idList`` if
        they are not already present.

    Returns
    -------
    measCat : `lsst.afw.table.SourceCatalog`
        Catalog prepopulated with entries with the IDs specified.
    """

    if not isinstance(schema, Schema):
        raise RuntimeError("schema must be an instance of "
                           "lsst.afw.table.Schema")

    if not isinstance(oldCatalog, SourceCatalog):
        raise RuntimeError("oldCatalog must be an instance of "
                           "lsst.afw.table.SourceCatalogiterable")

    if fields is None:
        fields = []
    if not isinstance(fields, Iterable):
        raise RuntimeError("fields list must be an iterable with string"
                           "elements")
    for entry in fields:
        if entry not in schema:
            schema.addField(oldCatalog.schema.find(entry).field)

    if addParents:
        newIdList = set()
        for srcId in idList:
            newIdList.add(srcId)
            parentId = oldCatalog.find(srcId).getParent()
            if parentId:
                newIdList.add(parentId)
        idList = newIdList
    idList = sorted(idList)

    measCat = SourceCatalog(schema)
    for srcId in idList:
        oldSrc = oldCatalog.find(srcId)
        src = measCat.addNew()
        src.setId(srcId)
        src.setFootprint(oldSrc.getFootprint())
        parent = oldSrc.getParent()
        if resetParents and parent and parent not in idList:
            parent = 0
        src.setParent(parent)
        src.setCoord(oldSrc.getCoord())
        for entry in fields:
            src[entry] = oldSrc[entry]
    return measCat