measureCrosstalk.py

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# This file is part of cp_pipe
#
# 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 <http://www.gnu.org/licenses/>.
import itertools
import numpy as np
 
from collections import defaultdict
 
import lsst.pipe.base as pipeBase
import lsst.pipe.base.connectionTypes as cT
 
from lsstDebug import getDebugFrame
from lsst.afw.detection import FootprintSet, Threshold
from lsst.afw.display import getDisplay
from lsst.pex.config import Config, Field, ListField, ConfigurableField
from lsst.ip.isr import CrosstalkCalib, IsrProvenance
from lsst.pipe.tasks.getRepositoryData import DataRefListRunner
from lsst.cp.pipe.utils import (ddict2dict, sigmaClipCorrection)
 
from ._lookupStaticCalibration import lookupStaticCalibration
 
__all__ = ["CrosstalkExtractConfig", "CrosstalkExtractTask",
           "CrosstalkSolveTask", "CrosstalkSolveConfig",
           "MeasureCrosstalkConfig", "MeasureCrosstalkTask"]
 
 
class CrosstalkExtractConnections(pipeBase.PipelineTaskConnections,
                                  dimensions=("instrument", "exposure", "detector")):
    inputExp = cT.Input(
        name="crosstalkInputs",
        doc="Input post-ISR processed exposure to measure crosstalk from.",
        storageClass="Exposure",
        dimensions=("instrument", "exposure", "detector"),
        multiple=False,
    )
    # TODO: Depends on DM-21904.
    sourceExp = cT.Input(
        name="crosstalkSource",
        doc="Post-ISR exposure to measure for inter-chip crosstalk onto inputExp.",
        storageClass="Exposure",
        dimensions=("instrument", "exposure", "detector"),
        multiple=True,
        deferLoad=True,
        # lookupFunction=None,
    )
 
    outputRatios = cT.Output(
        name="crosstalkRatios",
        doc="Extracted crosstalk pixel ratios.",
        storageClass="StructuredDataDict",
        dimensions=("instrument", "exposure", "detector"),
    )
    outputFluxes = cT.Output(
        name="crosstalkFluxes",
        doc="Source pixel fluxes used in ratios.",
        storageClass="StructuredDataDict",
        dimensions=("instrument", "exposure", "detector"),
    )
 
    def __init__(self, *, config=None):
        super().__init__(config=config)
        # Discard sourceExp until DM-21904 allows full interchip
        # measurements.
        self.inputs.discard("sourceExp")
 
 
class CrosstalkExtractConfig(pipeBase.PipelineTaskConfig,
                             pipelineConnections=CrosstalkExtractConnections):
    """Configuration for the measurement of pixel ratios.
    """
    doMeasureInterchip = Field(
        dtype=bool,
        default=False,
        doc="Measure inter-chip crosstalk as well?",
    )
    threshold = Field(
        dtype=float,
        default=30000,
        doc="Minimum level of source pixels for which to measure crosstalk."
    )
    ignoreSaturatedPixels = Field(
        dtype=bool,
        default=True,
        doc="Should saturated pixels be ignored?"
    )
    badMask = ListField(
        dtype=str,
        default=["BAD", "INTRP"],
        doc="Mask planes to ignore when identifying source pixels."
    )
    isTrimmed = Field(
        dtype=bool,
        default=True,
        doc="Is the input exposure trimmed?"
    )
 
    def validate(self):
        super().validate()
 
        # Ensure the handling of the SAT mask plane is consistent
        # with the ignoreSaturatedPixels value.
        if self.ignoreSaturatedPixelsignoreSaturatedPixels:
            if 'SAT' not in self.badMaskbadMask:
                self.badMaskbadMask.append('SAT')
        else:
            if 'SAT' in self.badMaskbadMask:
                self.badMaskbadMask = [mask for mask in self.badMaskbadMask if mask != 'SAT']
 
 
class CrosstalkExtractTask(pipeBase.PipelineTask,
                           pipeBase.CmdLineTask):
    """Task to measure pixel ratios to find crosstalk.
    """
    ConfigClass = CrosstalkExtractConfig
    _DefaultName = 'cpCrosstalkExtract'
 
    def run(self, inputExp, sourceExps=[]):
        """Measure pixel ratios between amplifiers in inputExp.
 
        Extract crosstalk ratios between different amplifiers.
 
        For pixels above ``config.threshold``, we calculate the ratio
        between each background-subtracted target amp and the source
        amp. We return a list of ratios for each pixel for each
        target/source combination, as nested dictionary containing the
        ratio.
 
        Parameters
        ----------
        inputExp : `lsst.afw.image.Exposure`
            Input exposure to measure pixel ratios on.
        sourceExp : `list` [`lsst.afw.image.Exposure`], optional
            List of chips to use as sources to measure inter-chip
            crosstalk.
 
        Returns
        -------
        results : `lsst.pipe.base.Struct`
            The results struct containing:
 
            ``outputRatios`` : `dict` [`dict` [`dict` [`dict` [`list`]]]]
                 A catalog of ratio lists.  The dictionaries are
                 indexed such that:
                 outputRatios[targetChip][sourceChip][targetAmp][sourceAmp]
                 contains the ratio list for that combination.
            ``outputFluxes`` : `dict` [`dict` [`list`]]
                 A catalog of flux lists.  The dictionaries are
                 indexed such that:
                 outputFluxes[sourceChip][sourceAmp]
                 contains the flux list used in the outputRatios.
 
        Notes
        -----
        The lsstDebug.Info() method can be rewritten for __name__ =
        `lsst.cp.pipe.measureCrosstalk`, and supports the parameters:
 
        debug.display['extract'] : `bool`
            Display the exposure under consideration, with the pixels used
            for crosstalk measurement indicated by the DETECTED mask plane.
        debug.display['pixels'] : `bool`
            Display a plot of the ratio calculated for each pixel used in this
            exposure, split by amplifier pairs.  The median value is listed
            for reference.
        """
        outputRatios = defaultdict(lambda: defaultdict(dict))
        outputFluxes = defaultdict(lambda: defaultdict(dict))
 
        threshold = self.config.threshold
        badPixels = list(self.config.badMask)
 
        targetDetector = inputExp.getDetector()
        targetChip = targetDetector.getName()
 
        # Always look at the target chip first, then go to any other supplied exposures.
        sourceExtractExps = [inputExp]
        sourceExtractExps.extend(sourceExps)
 
        self.log.info("Measuring full detector background for target: %s", targetChip)
        targetIm = inputExp.getMaskedImage()
        FootprintSet(targetIm, Threshold(threshold), "DETECTED")
        detected = targetIm.getMask().getPlaneBitMask("DETECTED")
        bg = CrosstalkCalib.calculateBackground(targetIm, badPixels + ["DETECTED"])
 
        self.debugViewdebugView('extract', inputExp)
 
        for sourceExp in sourceExtractExps:
            sourceDetector = sourceExp.getDetector()
            sourceChip = sourceDetector.getName()
            sourceIm = sourceExp.getMaskedImage()
            bad = sourceIm.getMask().getPlaneBitMask(badPixels)
            self.log.info("Measuring crosstalk from source: %s", sourceChip)
 
            if sourceExp != inputExp:
                FootprintSet(sourceIm, Threshold(threshold), "DETECTED")
                detected = sourceIm.getMask().getPlaneBitMask("DETECTED")
 
            # The dictionary of amp-to-amp ratios for this pair of source->target detectors.
            ratioDict = defaultdict(lambda: defaultdict(list))
            extractedCount = 0
 
            for sourceAmp in sourceDetector:
                sourceAmpName = sourceAmp.getName()
                sourceAmpBBox = sourceAmp.getBBox() if self.config.isTrimmed else sourceAmp.getRawDataBBox()
                sourceAmpImage = sourceIm[sourceAmpBBox]
                sourceMask = sourceAmpImage.mask.array
                select = ((sourceMask & detected > 0)
                          & (sourceMask & bad == 0)
                          & np.isfinite(sourceAmpImage.image.array))
                count = np.sum(select)
                self.log.debug("  Source amplifier: %s", sourceAmpName)
 
                outputFluxes[sourceChip][sourceAmpName] = sourceAmpImage.image.array[select].tolist()
 
                for targetAmp in targetDetector:
                    # iterate over targetExposure
                    targetAmpName = targetAmp.getName()
                    if sourceAmpName == targetAmpName and sourceChip == targetChip:
                        ratioDict[sourceAmpName][targetAmpName] = []
                        continue
                    self.log.debug("    Target amplifier: %s", targetAmpName)
 
                    targetAmpImage = CrosstalkCalib.extractAmp(targetIm.image,
                                                               targetAmp, sourceAmp,
                                                               isTrimmed=self.config.isTrimmed)
                    ratios = (targetAmpImage.array[select] - bg)/sourceAmpImage.image.array[select]
                    ratioDict[targetAmpName][sourceAmpName] = ratios.tolist()
                    extractedCount += count
 
                    self.debugPixelsdebugPixels('pixels',
                                     sourceAmpImage.image.array[select],
                                     targetAmpImage.array[select] - bg,
                                     sourceAmpName, targetAmpName)
 
            self.log.info("Extracted %d pixels from %s -> %s (targetBG: %f)",
                          extractedCount, sourceChip, targetChip, bg)
            outputRatios[targetChip][sourceChip] = ratioDict
 
        return pipeBase.Struct(
            outputRatios=ddict2dict(outputRatios),
            outputFluxes=ddict2dict(outputFluxes)
        )
 
    def debugView(self, stepname, exposure):
        """Utility function to examine the image being processed.
 
        Parameters
        ----------
        stepname : `str`
            State of processing to view.
        exposure : `lsst.afw.image.Exposure`
            Exposure to view.
        """
        frame = getDebugFrame(self._display, stepname)
        if frame:
            display = getDisplay(frame)
            display.scale('asinh', 'zscale')
            display.mtv(exposure)
 
            prompt = "Press Enter to continue: "
            while True:
                ans = input(prompt).lower()
                if ans in ("", "c",):
                    break
 
    def debugPixels(self, stepname, pixelsIn, pixelsOut, sourceName, targetName):
        """Utility function to examine the CT ratio pixel values.
 
        Parameters
        ----------
        stepname : `str`
            State of processing to view.
        pixelsIn : `np.ndarray`
            Pixel values from the potential crosstalk source.
        pixelsOut : `np.ndarray`
            Pixel values from the potential crosstalk target.
        sourceName : `str`
            Source amplifier name
        targetName : `str`
            Target amplifier name
        """
        frame = getDebugFrame(self._display, stepname)
        if frame:
            import matplotlib.pyplot as plt
            figure = plt.figure(1)
            figure.clear()
 
            axes = figure.add_axes((0.1, 0.1, 0.8, 0.8))
            axes.plot(pixelsIn, pixelsOut / pixelsIn, 'k+')
            plt.xlabel("Source amplifier pixel value")
            plt.ylabel("Measured pixel ratio")
            plt.title(f"(Source {sourceName} -> Target {targetName}) median ratio: "
                      f"{(np.median(pixelsOut / pixelsIn))}")
            figure.show()
 
            prompt = "Press Enter to continue: "
            while True:
                ans = input(prompt).lower()
                if ans in ("", "c",):
                    break
            plt.close()
 
 
class CrosstalkSolveConnections(pipeBase.PipelineTaskConnections,
                                dimensions=("instrument", "detector")):
    inputRatios = cT.Input(
        name="crosstalkRatios",
        doc="Ratios measured for an input exposure.",
        storageClass="StructuredDataDict",
        dimensions=("instrument", "exposure", "detector"),
        multiple=True,
    )
    inputFluxes = cT.Input(
        name="crosstalkFluxes",
        doc="Fluxes of CT source pixels, for nonlinear fits.",
        storageClass="StructuredDataDict",
        dimensions=("instrument", "exposure", "detector"),
        multiple=True,
    )
    camera = cT.PrerequisiteInput(
        name="camera",
        doc="Camera the input data comes from.",
        storageClass="Camera",
        dimensions=("instrument",),
        isCalibration=True,
        lookupFunction=lookupStaticCalibration,
    )
 
    outputCrosstalk = cT.Output(
        name="crosstalk",
        doc="Output proposed crosstalk calibration.",
        storageClass="CrosstalkCalib",
        dimensions=("instrument", "detector"),
        multiple=False,
        isCalibration=True,
    )
 
    def __init__(self, *, config=None):
        super().__init__(config=config)
 
        if config.fluxOrder == 0:
            self.inputs.discard("inputFluxes")
 
 
class CrosstalkSolveConfig(pipeBase.PipelineTaskConfig,
                           pipelineConnections=CrosstalkSolveConnections):
    """Configuration for the solving of crosstalk from pixel ratios.
    """
    rejIter = Field(
        dtype=int,
        default=3,
        doc="Number of rejection iterations for final coefficient calculation.",
    )
    rejSigma = Field(
        dtype=float,
        default=2.0,
        doc="Rejection threshold (sigma) for final coefficient calculation.",
    )
    fluxOrder = Field(
        dtype=int,
        default=0,
        doc="Polynomial order in source flux to fit crosstalk.",
    )
    doFiltering = Field(
        dtype=bool,
        default=False,
        doc="Filter generated crosstalk to remove marginal measurements.",
    )
 
 
class CrosstalkSolveTask(pipeBase.PipelineTask,
                         pipeBase.CmdLineTask):
    """Task to solve crosstalk from pixel ratios.
    """
    ConfigClass = CrosstalkSolveConfig
    _DefaultName = 'cpCrosstalkSolve'
 
    def runQuantum(self, butlerQC, inputRefs, outputRefs):
        """Ensure that the input and output dimensions are passed along.
 
        Parameters
        ----------
        butlerQC : `lsst.daf.butler.butlerQuantumContext.ButlerQuantumContext`
            Butler to operate on.
        inputRefs : `lsst.pipe.base.connections.InputQuantizedConnection`
            Input data refs to load.
        ouptutRefs : `lsst.pipe.base.connections.OutputQuantizedConnection`
            Output data refs to persist.
        """
        inputs = butlerQC.get(inputRefs)
 
        # Use the dimensions to set calib/provenance information.
        inputs['inputDims'] = [exp.dataId.byName() for exp in inputRefs.inputRatios]
        inputs['outputDims'] = outputRefs.outputCrosstalk.dataId.byName()
 
        outputs = self.runrun(**inputs)
        butlerQC.put(outputs, outputRefs)
 
    def run(self, inputRatios, inputFluxes=None, camera=None, inputDims=None, outputDims=None):
        """Combine ratios to produce crosstalk coefficients.
 
        Parameters
        ----------
        inputRatios : `list` [`dict` [`dict` [`dict` [`dict` [`list`]]]]]
            A list of nested dictionaries of ratios indexed by target
            and source chip, then by target and source amplifier.
        inputFluxes : `list` [`dict` [`dict` [`list`]]]
            A list of nested dictionaries of source pixel fluxes, indexed
            by source chip and amplifier.
        camera : `lsst.afw.cameraGeom.Camera`
            Input camera.
        inputDims : `list` [`lsst.daf.butler.DataCoordinate`]
            DataIds to use to construct provenance.
        outputDims : `list` [`lsst.daf.butler.DataCoordinate`]
            DataIds to use to populate the output calibration.
 
        Returns
        -------
        results : `lsst.pipe.base.Struct`
            The results struct containing:
 
            ``outputCrosstalk`` : `lsst.ip.isr.CrosstalkCalib`
                Final crosstalk calibration.
            ``outputProvenance`` : `lsst.ip.isr.IsrProvenance`
                Provenance data for the new calibration.
 
        Raises
        ------
        RuntimeError
            Raised if the input data contains multiple target detectors.
 
        Notes
        -----
        The lsstDebug.Info() method can be rewritten for __name__ =
        `lsst.ip.isr.measureCrosstalk`, and supports the parameters:
 
        debug.display['reduce'] : `bool`
            Display a histogram of the combined ratio measurements for
            a pair of source/target amplifiers from all input
            exposures/detectors.
 
        """
        if outputDims:
            calibChip = outputDims['detector']
            instrument = outputDims['instrument']
        else:
            # calibChip needs to be set manually in Gen2.
            calibChip = None
            instrument = None
 
        if camera and calibChip:
            calibDetector = camera[calibChip]
        else:
            calibDetector = None
 
        self.log.info("Combining measurements from %d ratios and %d fluxes",
                      len(inputRatios), len(inputFluxes) if inputFluxes else 0)
 
        if inputFluxes is None:
            inputFluxes = [None for exp in inputRatios]
 
        combinedRatios = defaultdict(lambda: defaultdict(list))
        combinedFluxes = defaultdict(lambda: defaultdict(list))
        for ratioDict, fluxDict in zip(inputRatios, inputFluxes):
            for targetChip in ratioDict:
                if calibChip and targetChip != calibChip and targetChip != calibDetector.getName():
                    raise RuntimeError(f"Target chip: {targetChip} does not match calibration dimension: "
                                       f"{calibChip}, {calibDetector.getName()}!")
 
                sourceChip = targetChip
                if sourceChip in ratioDict[targetChip]:
                    ratios = ratioDict[targetChip][sourceChip]
 
                    for targetAmp in ratios:
                        for sourceAmp in ratios[targetAmp]:
                            combinedRatios[targetAmp][sourceAmp].extend(ratios[targetAmp][sourceAmp])
                            if fluxDict:
                                combinedFluxes[targetAmp][sourceAmp].extend(fluxDict[sourceChip][sourceAmp])
                # TODO: DM-21904
                # Iterating over all other entries in ratioDict[targetChip] will yield
                # inter-chip terms.
 
        for targetAmp in combinedRatios:
            for sourceAmp in combinedRatios[targetAmp]:
                self.log.info("Read %d pixels for %s -> %s",
                              len(combinedRatios[targetAmp][sourceAmp]),
                              targetAmp, sourceAmp)
                if len(combinedRatios[targetAmp][sourceAmp]) > 1:
                    self.debugRatiosdebugRatios('reduce', combinedRatios, targetAmp, sourceAmp)
 
        if self.config.fluxOrder == 0:
            self.log.info("Fitting crosstalk coefficients.")
            calib = self.measureCrosstalkCoefficientsmeasureCrosstalkCoefficients(combinedRatios,
                                                      self.config.rejIter, self.config.rejSigma)
        else:
            raise NotImplementedError("Non-linear crosstalk terms are not yet supported.")
 
        self.log.info("Number of valid coefficients: %d", np.sum(calib.coeffValid))
 
        if self.config.doFiltering:
            # This step will apply the calculated validity values to
            # censor poorly measured coefficients.
            self.log.info("Filtering measured crosstalk to remove invalid solutions.")
            calib = self.filterCrosstalkCalibfilterCrosstalkCalib(calib)
 
        # Populate the remainder of the calibration information.
        calib.hasCrosstalk = True
        calib.interChip = {}
 
        # calibChip is the detector dimension, which is the detector Id
        calib._detectorId = calibChip
        if calibDetector:
            calib._detectorName = calibDetector.getName()
            calib._detectorSerial = calibDetector.getSerial()
 
        calib._instrument = instrument
        calib.updateMetadata(setCalibId=True, setDate=True)
 
        # Make an IsrProvenance().
        provenance = IsrProvenance(calibType="CROSSTALK")
        provenance._detectorName = calibChip
        if inputDims:
            provenance.fromDataIds(inputDims)
            provenance._instrument = instrument
        provenance.updateMetadata()
 
        return pipeBase.Struct(
            outputCrosstalk=calib,
            outputProvenance=provenance,
        )
 
    def measureCrosstalkCoefficients(self, ratios, rejIter, rejSigma):
        """Measure crosstalk coefficients from the ratios.
 
        Given a list of ratios for each target/source amp combination,
        we measure a sigma clipped mean and error.
 
        The coefficient errors returned are the standard deviation of
        the final set of clipped input ratios.
 
        Parameters
        ----------
        ratios : `dict` of `dict` of `numpy.ndarray`
           Catalog of arrays of ratios.
        rejIter : `int`
           Number of rejection iterations.
        rejSigma : `float`
           Rejection threshold (sigma).
 
        Returns
        -------
        calib : `lsst.ip.isr.CrosstalkCalib`
            The output crosstalk calibration.
 
        Notes
        -----
        The lsstDebug.Info() method can be rewritten for __name__ =
        `lsst.ip.isr.measureCrosstalk`, and supports the parameters:
 
        debug.display['measure'] : `bool`
            Display the CDF of the combined ratio measurements for
            a pair of source/target amplifiers from the final set of
            clipped input ratios.
        """
        calib = CrosstalkCalib(nAmp=len(ratios))
 
        # Calibration stores coefficients as a numpy ndarray.
        ordering = list(ratios.keys())
        for ii, jj in itertools.product(range(calib.nAmp), range(calib.nAmp)):
            if ii == jj:
                values = [0.0]
            else:
                values = np.array(ratios[ordering[ii]][ordering[jj]])
                values = values[np.abs(values) < 1.0]  # Discard unreasonable values
 
            calib.coeffNum[ii][jj] = len(values)
 
            if len(values) == 0:
                self.log.warn("No values for matrix element %d,%d" % (ii, jj))
                calib.coeffs[ii][jj] = np.nan
                calib.coeffErr[ii][jj] = np.nan
                calib.coeffValid[ii][jj] = False
            else:
                if ii != jj:
                    for rej in range(rejIter):
                        lo, med, hi = np.percentile(values, [25.0, 50.0, 75.0])
                        sigma = 0.741*(hi - lo)
                        good = np.abs(values - med) < rejSigma*sigma
                        if good.sum() == len(good):
                            break
                        values = values[good]
 
                calib.coeffs[ii][jj] = np.mean(values)
                if calib.coeffNum[ii][jj] == 1:
                    calib.coeffErr[ii][jj] = np.nan
                else:
                    correctionFactor = sigmaClipCorrection(rejSigma)
                    calib.coeffErr[ii][jj] = np.std(values) * correctionFactor
                calib.coeffValid[ii][jj] = (np.abs(calib.coeffs[ii][jj])
                                            > calib.coeffErr[ii][jj] / np.sqrt(calib.coeffNum[ii][jj]))
 
            if calib.coeffNum[ii][jj] > 1:
                self.debugRatiosdebugRatios('measure', ratios, ordering[ii], ordering[jj],
                                 calib.coeffs[ii][jj], calib.coeffValid[ii][jj])
 
        return calib
 
    @staticmethod
    def filterCrosstalkCalib(inCalib):
        """Apply valid constraints to the measured values.
 
        Any measured coefficient that is determined to be invalid is
        set to zero, and has the error set to nan.  The validation is
        determined by checking that the measured coefficient is larger
        than the calculated standard error of the mean.
 
        Parameters
        ----------
        inCalib : `lsst.ip.isr.CrosstalkCalib`
            Input calibration to filter.
 
        Returns
        -------
        outCalib : `lsst.ip.isr.CrosstalkCalib`
             Filtered calibration.
        """
        outCalib = CrosstalkCalib()
        outCalib.numAmps = inCalib.numAmps
 
        outCalib.coeffs = inCalib.coeffs
        outCalib.coeffs[~inCalib.coeffValid] = 0.0
 
        outCalib.coeffErr = inCalib.coeffErr
        outCalib.coeffErr[~inCalib.coeffValid] = np.nan
 
        outCalib.coeffNum = inCalib.coeffNum
        outCalib.coeffValid = inCalib.coeffValid
 
        return outCalib
 
    def debugRatios(self, stepname, ratios, i, j, coeff=0.0, valid=False):
        """Utility function to examine the final CT ratio set.
 
        Parameters
        ----------
        stepname : `str`
            State of processing to view.
        ratios : `dict` of `dict` of `np.ndarray`
            Array of measured CT ratios, indexed by source/victim
            amplifier.
        i : `str`
            Index of the source amplifier.
        j : `str`
            Index of the target amplifier.
        coeff : `float`, optional
            Coefficient calculated to plot along with the simple mean.
        valid : `bool`, optional
            Validity to be added to the plot title.
        """
        frame = getDebugFrame(self._display, stepname)
        if frame:
            if i == j or ratios is None or len(ratios) < 1:
                pass
 
            ratioList = ratios[i][j]
            if ratioList is None or len(ratioList) < 1:
                pass
 
            mean = np.mean(ratioList)
            std = np.std(ratioList)
            import matplotlib.pyplot as plt
            figure = plt.figure(1)
            figure.clear()
            plt.hist(x=ratioList, bins=len(ratioList),
                     cumulative=True, color='b', density=True, histtype='step')
            plt.xlabel("Measured pixel ratio")
            plt.ylabel(f"CDF: n={len(ratioList)}")
            plt.xlim(np.percentile(ratioList, [1.0, 99]))
            plt.axvline(x=mean, color="k")
            plt.axvline(x=coeff, color='g')
            plt.axvline(x=(std / np.sqrt(len(ratioList))), color='r')
            plt.axvline(x=-(std / np.sqrt(len(ratioList))), color='r')
            plt.title(f"(Source {i} -> Target {j}) mean: {mean:.2g} coeff: {coeff:.2g} valid: {valid}")
            figure.show()
 
            prompt = "Press Enter to continue: "
            while True:
                ans = input(prompt).lower()
                if ans in ("", "c",):
                    break
                elif ans in ("pdb", "p",):
                    import pdb
                    pdb.set_trace()
            plt.close()
 
 
class MeasureCrosstalkConfig(Config):
    extract = ConfigurableField(
        target=CrosstalkExtractTask,
        doc="Task to measure pixel ratios.",
    )
    solver = ConfigurableField(
        target=CrosstalkSolveTask,
        doc="Task to convert ratio lists to crosstalk coefficients.",
    )
 
 
class MeasureCrosstalkTask(pipeBase.CmdLineTask):
    """Measure intra-detector crosstalk.
 
    See also
    --------
    lsst.ip.isr.crosstalk.CrosstalkCalib
    lsst.cp.pipe.measureCrosstalk.CrosstalkExtractTask
    lsst.cp.pipe.measureCrosstalk.CrosstalkSolveTask
 
    Notes
    -----
    The crosstalk this method measures assumes that when a bright
    pixel is found in one detector amplifier, all other detector
    amplifiers may see a signal change in the same pixel location
    (relative to the readout amplifier) as these other pixels are read
    out at the same time.
 
    After processing each input exposure through a limited set of ISR
    stages, bright unmasked pixels above the threshold are identified.
    The potential CT signal is found by taking the ratio of the
    appropriate background-subtracted pixel value on the other
    amplifiers to the input value on the source amplifier.  If the
    source amplifier has a large number of bright pixels as well, the
    background level may be elevated, leading to poor ratio
    measurements.
 
    The set of ratios found between each pair of amplifiers across all
    input exposures is then gathered to produce the final CT
    coefficients.  The sigma-clipped mean and sigma are returned from
    these sets of ratios, with the coefficient to supply to the ISR
    CrosstalkTask() being the multiplicative inverse of these values.
 
    This Task simply calls the pipetask versions of the measure
    crosstalk code.
    """
    ConfigClass = MeasureCrosstalkConfig
    _DefaultName = "measureCrosstalk"
 
    # Let's use this instead of messing with parseAndRun.
    RunnerClass = DataRefListRunner
 
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.makeSubtask("extract")
        self.makeSubtask("solver")
 
    def runDataRef(self, dataRefList):
        """Run extract task on each of inputs in the dataRef list, then pass
        that to the solver task.
 
        Parameters
        ----------
        dataRefList : `list` [`lsst.daf.peristence.ButlerDataRef`]
            Data references for exposures for detectors to process.
 
        Returns
        -------
        results : `lsst.pipe.base.Struct`
            The results struct containing:
 
            ``outputCrosstalk`` : `lsst.ip.isr.CrosstalkCalib`
                Final crosstalk calibration.
            ``outputProvenance`` : `lsst.ip.isr.IsrProvenance`
                Provenance data for the new calibration.
 
        Raises
        ------
        RuntimeError
            Raised if multiple target detectors are supplied.
        """
        dataRef = dataRefList[0]
        camera = dataRef.get("camera")
 
        ratios = []
        activeChip = None
        for dataRef in dataRefList:
            exposure = dataRef.get("postISRCCD")
            if activeChip:
                if exposure.getDetector().getName() != activeChip:
                    raise RuntimeError("Too many input detectors supplied!")
            else:
                activeChip = exposure.getDetector().getName()
 
            self.extract.debugView("extract", exposure)
            result = self.extract.run(exposure)
            ratios.append(result.outputRatios)
 
        for detIter, detector in enumerate(camera):
            if detector.getName() == activeChip:
                detectorId = detIter
        outputDims = {'instrument': camera.getName(),
                      'detector': detectorId,
                      }
 
        finalResults = self.solver.run(ratios, camera=camera, outputDims=outputDims)
        dataRef.put(finalResults.outputCrosstalk, "crosstalk")
 
        return finalResults