CompareWarpAssembleCoaddConfig

class lsst.pipe.tasks.assembleCoadd.CompareWarpAssembleCoaddConfig(*args, **kw)

Bases: AssembleCoaddConfig

Attributes Summary

assembleStaticSkyModel	Task to assemble an artifact-free, PSF-matched Coadd to serve as a naive/first-iteration model of the static sky.
badMaskPlanes	Mask planes that, if set, the associated pixel should not be included in the coaddTempExp.
brightObjectMaskName	Name of mask bit used for bright objects (str, default 'BRIGHT_OBJECT')
calcErrorFromInputVariance	Calculate coadd variance from input variance by stacking statistic.Passed to StatisticsControl.setCalcErrorFromInputVariance() (bool, default True)
clipIter	Number of iterations of outlier rejection; ignored if non-clipping statistic selected.
coaddName	Coadd name: typically one of deep or goodSeeing.
coaddPsf	Configuration for CoaddPsf (CoaddPsfConfig, default <class 'lsst.meas.algorithms.CoaddPsfConfig'>)
connections	Field which refers to a dynamically added configuration class which is based on a PipelineTaskConnections class.
detect	Detect outlier sources on difference between each psfMatched warp and static sky model (ConfigurableInstance, default <class 'lsst.meas.algorithms.detection.SourceDetectionConfig'>)
detectTemplate	Detect sources on static sky model.
doApplyExternalPhotoCalib	Whether to apply external photometric calibration via an lsst.afw.image.PhotoCalib object.
doApplyExternalSkyWcs	Whether to apply external astrometric calibration via an lsst.afw.geom.SkyWcs object.
doAttachTransmissionCurve	Attach a piecewise TransmissionCurve for the coadd? (requires all input Exposures to have TransmissionCurves).
doFilterMorphological	Filter artifact candidates based on morphological criteria, i.g.
doInputMap	Create a bitwise map of coadd inputs (bool, default False)
doInterp	Interpolate over NaN pixels? Also extrapolate, if necessary, but the results are ugly.
doMaskBrightObjects	Set mask and flag bits for bright objects? (bool, default False)
doNImage	Create image of number of contributing exposures for each pixel (bool, default False)
doOnlineForMean	Perform online coaddition when statistic="MEAN" to save memory? (bool, default False)
doPrefilterArtifacts	Ignore artifact candidates that are mostly covered by the bad pixel mask, because they will be excluded anyway.
doPreserveContainedBySource	Rescue artifacts from clipping that completely lie within a footprint detectedon the PsfMatched Template Coadd.
doPsfMatch	Match to modelPsf? Sets makePsfMatched=True, makeDirect=False Deprecated: This field is no longer used.
doScaleWarpVariance	Rescale Warp variance plane using empirical noise? (bool, default True)
doSelectVisits	Coadd only visits selected by a SelectVisitsTask (bool, default False)
doSigmaClip	Perform sigma clipped outlier rejection with MEANCLIP statistic? (DEPRECATED) (bool, default False)
doUsePsfMatchedPolygons	Use ValidPolygons from shrunk Psf-Matched Calexps? Should be set to True by CompareWarp only.
doWrite	Persist coadd? (bool, default True)
growStreakFp	Grow streak footprints by this number multiplied by the PSF width (float, default 5)
hasFakes	Should be set to True if fake sources have been inserted into the input data.
history
includeCalibVar	Add photometric calibration variance to warp variance plane.
inputMapper	Input map creation subtask.
inputRecorder	Subtask that helps fill CoaddInputs catalogs added to the final Exposure (ConfigurableInstance, default <class 'lsst.pipe.tasks.coaddInputRecorder.CoaddInputRecorderConfig'>)
interpImage	Task to interpolate (and extrapolate) over NaN pixels (ConfigurableInstance, default <class 'lsst.pipe.tasks.interpImage.InterpImageConfig'>)
maskPropagationThresholds	Threshold (in fractional weight) of rejection at which we propagate a mask plane to the coadd; that is, we set the mask bit on the coadd if the fraction the rejected frames would have contributed exceeds this value.
maskStreaks	Detect streaks on difference between each psfMatched warp and static sky model.
matchingKernelSize	Size in pixels of matching kernel.
maxFractionEpochsHigh	Fraction of local number of epochs (N) to use as effective maxNumEpochs for high N.
maxFractionEpochsLow	Fraction of local number of epochs (N) to use as effective maxNumEpochs for low N.
maxNumEpochs	Charactistic maximum local number of epochs/visits in which an artifact candidate can appear and still be masked.
modelPsf	Model Psf factory (ConfigurableInstance, default <class 'lsst.meas.algorithms.gaussianPsfFactory.GaussianPsfFactory'>)
prefilterArtifactsMaskPlanes	Prefilter artifact candidates that are mostly covered by these bad mask planes.
prefilterArtifactsRatio	Prefilter artifact candidates with less than this fraction overlapping good pixels (float, default 0.05)
removeMaskPlanes	Mask planes to remove before coadding (List, default ['NOT_DEBLENDED'])
saveLogOutput	Flag to enable/disable saving of log output for a task, enabled by default.
saveMetadata	Flag to enable/disable metadata saving for a task, enabled by default.
scaleWarpVariance	Rescale variance on warps (ConfigurableInstance, default <class 'lsst.meas.algorithms.scaleVariance.ScaleVarianceConfig'>)
scaleZeroPoint	Task to adjust the photometric zero point of the coadd temp exposures (ConfigurableInstance, default <class 'lsst.pipe.tasks.scaleZeroPoint.ScaleZeroPointConfig'>)
select	Image selection subtask.
sigmaClip	Sigma for outlier rejection; ignored if non-clipping statistic selected.
spatialThreshold	Unitless fraction of pixels defining how much of the outlier region has to meet the temporal criteria.
statistic	Main stacking statistic for aggregating over the epochs.
streakMaskName	Name of mask bit used for streaks (str, default 'STREAK')
subregionSize	Width, height of stack subregion size; make small enough that a full stack of images will fit into memory at once.
useGlobalExternalPhotoCalib	When using doApplyExternalPhotoCalib, use 'global' calibrations that are not run per-tract.
useGlobalExternalSkyWcs	When using doApplyExternalSkyWcs, use 'global' calibrations that are not run per-tract.
warpType	Warp name: one of 'direct' or 'psfMatched' (str, default 'direct')

Methods Summary

applyConfigOverrides(instrument, ...)	Apply config overrides to this config instance.
compare(other[, shortcut, rtol, atol, output])	Compare this configuration to another Config for equality.
formatHistory(name, **kwargs)	Format a configuration field's history to a human-readable format.
freeze()	Make this config, and all subconfigs, read-only.
items()	Get configurations as (field name, field value) pairs.
keys()	Get field names.
load(filename[, root])	Modify this config in place by executing the Python code in a configuration file.
loadFromStream(stream[, root, filename, ...])	Modify this Config in place by executing the Python code in the provided stream.
loadFromString(code[, root, filename, ...])	Modify this Config in place by executing the Python code in the provided string.
names()	Get all the field names in the config, recursively.
save(filename[, root])	Save a Python script to the named file, which, when loaded, reproduces this config.
saveToStream(outfile[, root, skipImports])	Save a configuration file to a stream, which, when loaded, reproduces this config.
saveToString([skipImports])	Return the Python script form of this configuration as an executable string.
setDefaults()	Subclass hook for computing defaults.
toDict()	Make a dictionary of field names and their values.
update(**kw)	Update values of fields specified by the keyword arguments.
validate()	Validate the Config, raising an exception if invalid.
values()	Get field values.

Attributes Documentation

assembleStaticSkyModel

Task to assemble an artifact-free, PSF-matched Coadd to serve as a naive/first-iteration model of the static sky. (ConfigurableInstance, default <class 'lsst.pipe.tasks.assembleCoadd.AssembleCoaddConfig'>)

badMaskPlanes

Mask planes that, if set, the associated pixel should not be included in the coaddTempExp. (List, default ('NO_DATA',))

brightObjectMaskName

Name of mask bit used for bright objects (str, default 'BRIGHT_OBJECT')

calcErrorFromInputVariance

Calculate coadd variance from input variance by stacking statistic.Passed to StatisticsControl.setCalcErrorFromInputVariance() (bool, default True)

clipIter

Number of iterations of outlier rejection; ignored if non-clipping statistic selected. (int, default 2)

coaddName

Coadd name: typically one of deep or goodSeeing. (str, default 'deep')

coaddPsf

Configuration for CoaddPsf (CoaddPsfConfig, default <class 'lsst.meas.algorithms.CoaddPsfConfig'>)

connections: pexConfig.ConfigField

Field which refers to a dynamically added configuration class which is based on a PipelineTaskConnections class.

detect

Detect outlier sources on difference between each psfMatched warp and static sky model (ConfigurableInstance, default <class 'lsst.meas.algorithms.detection.SourceDetectionConfig'>)

detectTemplate

Detect sources on static sky model. Only used if doPreserveContainedBySource is True (ConfigurableInstance, default <class 'lsst.meas.algorithms.detection.SourceDetectionConfig'>)

doApplyExternalPhotoCalib

Whether to apply external photometric calibration via an lsst.afw.image.PhotoCalib object. Uses the externalPhotoCalibName field to determine which calibration to load. Deprecated: Deprecated in favor of the ‘visitSummary’ connection. Will be removed after v26. (bool, default False)

doApplyExternalSkyWcs

Whether to apply external astrometric calibration via an lsst.afw.geom.SkyWcs object. Uses externalSkyWcsName field to determine which calibration to load. Deprecated: Deprecated in favor of the ‘visitSummary’ connection. Will be removed after v26. (bool, default False)

doAttachTransmissionCurve

Attach a piecewise TransmissionCurve for the coadd? (requires all input Exposures to have TransmissionCurves). (bool, default False)

doFilterMorphological

Filter artifact candidates based on morphological criteria, i.g. those that appear to be streaks. (bool, default False)

doInputMap

Create a bitwise map of coadd inputs (bool, default False)

doInterp

Interpolate over NaN pixels? Also extrapolate, if necessary, but the results are ugly. (bool, default True)

doMaskBrightObjects

Set mask and flag bits for bright objects? (bool, default False)

doNImage

Create image of number of contributing exposures for each pixel (bool, default False)

doOnlineForMean

Perform online coaddition when statistic=”MEAN” to save memory? (bool, default False)

doPrefilterArtifacts

Ignore artifact candidates that are mostly covered by the bad pixel mask, because they will be excluded anyway. This prevents them from contributing to the outlier epoch count image and potentially being labeled as persistant.’Mostly’ is defined by the config ‘prefilterArtifactsRatio’. (bool, default True)

doPreserveContainedBySource

Rescue artifacts from clipping that completely lie within a footprint detectedon the PsfMatched Template Coadd. Replicates a behavior of SafeClip. (bool, default True)

doPsfMatch

Match to modelPsf? Sets makePsfMatched=True, makeDirect=False Deprecated: This field is no longer used. Will be removed after v26. (bool, default False)

doScaleWarpVariance

Rescale Warp variance plane using empirical noise? (bool, default True)

doSelectVisits

Coadd only visits selected by a SelectVisitsTask (bool, default False)

doSigmaClip

Perform sigma clipped outlier rejection with MEANCLIP statistic? (DEPRECATED) (bool, default False)

doUsePsfMatchedPolygons

Use ValidPolygons from shrunk Psf-Matched Calexps? Should be set to True by CompareWarp only. (bool, default False)

doWrite

Persist coadd? (bool, default True)

growStreakFp

Grow streak footprints by this number multiplied by the PSF width (float, default 5)

hasFakes

Should be set to True if fake sources have been inserted into the input data. (bool, default False)

history

Read-only history.

includeCalibVar

Add photometric calibration variance to warp variance plane. (bool, default False)

inputMapper

Input map creation subtask. (ConfigurableInstance, default <class 'lsst.pipe.tasks.healSparseMapping.HealSparseInputMapConfig'>)

inputRecorder

Subtask that helps fill CoaddInputs catalogs added to the final Exposure (ConfigurableInstance, default <class 'lsst.pipe.tasks.coaddInputRecorder.CoaddInputRecorderConfig'>)

interpImage

Task to interpolate (and extrapolate) over NaN pixels (ConfigurableInstance, default <class 'lsst.pipe.tasks.interpImage.InterpImageConfig'>)

maskPropagationThresholds

Threshold (in fractional weight) of rejection at which we propagate a mask plane to the coadd; that is, we set the mask bit on the coadd if the fraction the rejected frames would have contributed exceeds this value. (Dict, default {'SAT': 0.1})

maskStreaks

Detect streaks on difference between each psfMatched warp and static sky model. Only used if doFilterMorphological is True. Adds a mask plane to an exposure, with the mask plane name set bystreakMaskName (ConfigurableInstance, default <class 'lsst.pipe.tasks.maskStreaks.MaskStreaksConfig'>)

matchingKernelSize

Size in pixels of matching kernel. Must be odd. (int, default 21)

maxFractionEpochsHigh

Fraction of local number of epochs (N) to use as effective maxNumEpochs for high N. Effective maxNumEpochs = min(maxFractionEpochsLow * N, maxNumEpochs + maxFractionEpochsHigh * N) (float, default 0.03)

Valid Range = [0.0,1.0)

maxFractionEpochsLow

Fraction of local number of epochs (N) to use as effective maxNumEpochs for low N. Effective maxNumEpochs = min(maxFractionEpochsLow * N, maxNumEpochs + maxFractionEpochsHigh * N) (float, default 0.4)

Valid Range = [0.0,1.0)

maxNumEpochs

Charactistic maximum local number of epochs/visits in which an artifact candidate can appear and still be masked. The effective maxNumEpochs is a broken linear function of local number of epochs (N): min(maxFractionEpochsLow*N, maxNumEpochs + maxFractionEpochsHigh*N). For each footprint detected on the image difference between the psfMatched warp and static sky model, if a significant fraction of pixels (defined by spatialThreshold) are residuals in more than the computed effective maxNumEpochs, the artifact candidate is deemed persistant rather than transient and not masked. (int, default 2)

modelPsf

Model Psf factory (ConfigurableInstance, default <class 'lsst.meas.algorithms.gaussianPsfFactory.GaussianPsfFactory'>)

prefilterArtifactsMaskPlanes

Prefilter artifact candidates that are mostly covered by these bad mask planes. (List, default ('NO_DATA', 'BAD', 'SAT', 'SUSPECT'))

prefilterArtifactsRatio

Prefilter artifact candidates with less than this fraction overlapping good pixels (float, default 0.05)

removeMaskPlanes

Mask planes to remove before coadding (List, default ['NOT_DEBLENDED'])

saveLogOutput

Flag to enable/disable saving of log output for a task, enabled by default. (bool, default True)

saveMetadata

Flag to enable/disable metadata saving for a task, enabled by default. Deprecated: This field is deprecated and will be removed after v26. (bool, default True)

scaleWarpVariance

Rescale variance on warps (ConfigurableInstance, default <class 'lsst.meas.algorithms.scaleVariance.ScaleVarianceConfig'>)

scaleZeroPoint

Task to adjust the photometric zero point of the coadd temp exposures (ConfigurableInstance, default <class 'lsst.pipe.tasks.scaleZeroPoint.ScaleZeroPointConfig'>)

select

Image selection subtask. (ConfigurableInstance, default <class 'lsst.pipe.tasks.selectImages.PsfWcsSelectImagesConfig'>)

sigmaClip

Sigma for outlier rejection; ignored if non-clipping statistic selected. (float, default 3.0)

spatialThreshold

Unitless fraction of pixels defining how much of the outlier region has to meet the temporal criteria. If 0, clip all. If 1, clip none. (float, default 0.5)

Valid Range = [0.0,1.0]

statistic

Main stacking statistic for aggregating over the epochs. (str, default 'MEANCLIP')

streakMaskName

Name of mask bit used for streaks (str, default 'STREAK')

subregionSize

Width, height of stack subregion size; make small enough that a full stack of images will fit into memory at once. (List, default (2000, 2000))

useGlobalExternalPhotoCalib

When using doApplyExternalPhotoCalib, use ‘global’ calibrations that are not run per-tract. When False, use per-tract photometric calibration files. Deprecated: Deprecated in favor of the ‘visitSummary’ connection. Will be removed after v26. (bool, default False)

useGlobalExternalSkyWcs

When using doApplyExternalSkyWcs, use ‘global’ calibrations that are not run per-tract. When False, use per-tract wcs files. Deprecated: Deprecated in favor of the ‘visitSummary’ connection. Will be removed after v26. (bool, default False)

warpType

Warp name: one of ‘direct’ or ‘psfMatched’ (str, default 'direct')

Methods Documentation

applyConfigOverrides(instrument: Instrument | None, taskDefaultName: str, pipelineConfigs: Iterable[ConfigIR] | None, parameters: ParametersIR, label: str) → None

Apply config overrides to this config instance.

Parameters:

instrumentInstrument or None

An instance of the Instrument specified in a pipeline. If None then the pipeline did not specify and instrument.

taskDefaultNamestr

The default name associated with the Task class. This may be used with instrumental overrides.

pipelineConfigsIterable of ConfigIR

An iterable of ConfigIR objects that contain overrides to apply to this config instance.

parametersParametersIR

Parameters defined in a Pipeline which are used in formatting of config values across multiple Task in a pipeline.

labelstr

The label associated with this class’s Task in a pipeline.

compare(other, shortcut=True, rtol=1e-08, atol=1e-08, output=None)

Compare this configuration to another Config for equality.

Parameters:

otherlsst.pex.config.Config

Other Config object to compare against this config.

shortcutbool, optional

If True, return as soon as an inequality is found. Default is True.

rtolfloat, optional

Relative tolerance for floating point comparisons.

atolfloat, optional

Absolute tolerance for floating point comparisons.

outputcallable, optional

A callable that takes a string, used (possibly repeatedly) to report inequalities.

Returns:

isEqualbool

True when the two lsst.pex.config.Config instances are equal. False if there is an inequality.

See also

lsst.pex.config.compareConfigs

Notes

Unselected targets of RegistryField fields and unselected choices of ConfigChoiceField fields are not considered by this method.

Floating point comparisons are performed by numpy.allclose.

formatHistory(name, **kwargs)

Format a configuration field’s history to a human-readable format.

Parameters:

namestr

Name of a Field in this config.

kwargs

Keyword arguments passed to lsst.pex.config.history.format.

Returns:

historystr

A string containing the formatted history.

See also

lsst.pex.config.history.format

freeze()

Make this config, and all subconfigs, read-only.

items()

Get configurations as (field name, field value) pairs.

Returns:

itemsItemsView

Iterator of tuples for each configuration. Tuple items are:

0. Field name.

1. Field value.

keys()

Get field names.

Returns:

namesKeysView

List of lsst.pex.config.Field names.

load(filename, root='config')

Modify this config in place by executing the Python code in a configuration file.

Parameters:

filenamestr

Name of the configuration file. A configuration file is Python module.

rootstr, optional

Name of the variable in file that refers to the config being overridden.

For example, the value of root is "config" and the file contains:

config.myField = 5

Then this config’s field myField is set to 5.

See also

lsst.pex.config.Config.loadFromStream

lsst.pex.config.Config.loadFromString

lsst.pex.config.Config.save

lsst.pex.config.Config.saveToStream

lsst.pex.config.Config.saveToString

loadFromStream(stream, root='config', filename=None, extraLocals=None)

Modify this Config in place by executing the Python code in the provided stream.

Parameters:

streamfile-like object, str, bytes, or compiled string

Stream containing configuration override code. If this is a code object, it should be compiled with mode="exec".

rootstr, optional

Name of the variable in file that refers to the config being overridden.

For example, the value of root is "config" and the file contains:

config.myField = 5

Then this config’s field myField is set to 5.

filenamestr, optional

Name of the configuration file, or None if unknown or contained in the stream. Used for error reporting.

extraLocalsdict of str to object, optional

Any extra variables to include in local scope when loading.

See also

lsst.pex.config.Config.load

lsst.pex.config.Config.loadFromString

lsst.pex.config.Config.save

lsst.pex.config.Config.saveToStream

lsst.pex.config.Config.saveToString

Notes

For backwards compatibility reasons, this method accepts strings, bytes and code objects as well as file-like objects. New code should use loadFromString instead for most of these types.

loadFromString(code, root='config', filename=None, extraLocals=None)

Modify this Config in place by executing the Python code in the provided string.

Parameters:

codestr, bytes, or compiled string

Stream containing configuration override code.

rootstr, optional

Name of the variable in file that refers to the config being overridden.

For example, the value of root is "config" and the file contains:

config.myField = 5

Then this config’s field myField is set to 5.

filenamestr, optional

Name of the configuration file, or None if unknown or contained in the stream. Used for error reporting.

extraLocalsdict of str to object, optional

Any extra variables to include in local scope when loading.

Raises:

ValueError

Raised if a key in extraLocals is the same value as the value of the root argument.

See also

lsst.pex.config.Config.load

lsst.pex.config.Config.loadFromStream

lsst.pex.config.Config.save

lsst.pex.config.Config.saveToStream

lsst.pex.config.Config.saveToString

names()

Get all the field names in the config, recursively.

Returns:

nameslist of str

Field names.

save(filename, root='config')

Save a Python script to the named file, which, when loaded, reproduces this config.

Parameters:

filenamestr

Desination filename of this configuration.

rootstr, optional

Name to use for the root config variable. The same value must be used when loading (see lsst.pex.config.Config.load).

See also

lsst.pex.config.Config.saveToStream

lsst.pex.config.Config.saveToString

lsst.pex.config.Config.load

lsst.pex.config.Config.loadFromStream

lsst.pex.config.Config.loadFromString

saveToStream(outfile, root='config', skipImports=False)

Save a configuration file to a stream, which, when loaded, reproduces this config.

Parameters:

outfilefile-like object

Destination file object write the config into. Accepts strings not bytes.

root

Name to use for the root config variable. The same value must be used when loading (see lsst.pex.config.Config.load).

skipImportsbool, optional

If True then do not include import statements in output, this is to support human-oriented output from pipetask where additional clutter is not useful.

See also

lsst.pex.config.Config.save

lsst.pex.config.Config.saveToString

lsst.pex.config.Config.load

lsst.pex.config.Config.loadFromStream

lsst.pex.config.Config.loadFromString

saveToString(skipImports=False)

Return the Python script form of this configuration as an executable string.

Parameters:

skipImportsbool, optional

If True then do not include import statements in output, this is to support human-oriented output from pipetask where additional clutter is not useful.

Returns:

codestr

A code string readable by loadFromString.

See also

lsst.pex.config.Config.save

lsst.pex.config.Config.saveToStream

lsst.pex.config.Config.load

lsst.pex.config.Config.loadFromStream

lsst.pex.config.Config.loadFromString

setDefaults()

Subclass hook for computing defaults.

Notes

Derived Config classes that must compute defaults rather than using the Field instances’s defaults should do so here. To correctly use inherited defaults, implementations of setDefaults must call their base class’s setDefaults.

toDict()

Make a dictionary of field names and their values.

Returns:

dict_dict

Dictionary with keys that are Field names. Values are Field values.

See also

lsst.pex.config.Field.toDict

Notes

This method uses the toDict method of individual fields. Subclasses of Field may need to implement a toDict method for this method to work.

update(**kw)

Update values of fields specified by the keyword arguments.

Parameters:

kw

Keywords are configuration field names. Values are configuration field values.

Notes

The __at and __label keyword arguments are special internal keywords. They are used to strip out any internal steps from the history tracebacks of the config. Do not modify these keywords to subvert a Config instance’s history.

Examples

This is a config with three fields:

>>> from lsst.pex.config import Config, Field
>>> class DemoConfig(Config):
...     fieldA = Field(doc='Field A', dtype=int, default=42)
...     fieldB = Field(doc='Field B', dtype=bool, default=True)
...     fieldC = Field(doc='Field C', dtype=str, default='Hello world')
...
>>> config = DemoConfig()

These are the default values of each field:

>>> for name, value in config.iteritems():
...     print(f"{name}: {value}")
...
fieldA: 42
fieldB: True
fieldC: 'Hello world'

Using this method to update fieldA and fieldC:

>>> config.update(fieldA=13, fieldC='Updated!')

Now the values of each field are:

>>> for name, value in config.iteritems():
...     print(f"{name}: {value}")
...
fieldA: 13
fieldB: True
fieldC: 'Updated!'

validate()

Validate the Config, raising an exception if invalid.

Raises:

lsst.pex.config.FieldValidationError

Raised if verification fails.

Notes

The base class implementation performs type checks on all fields by calling their validate methods.

Complex single-field validation can be defined by deriving new Field types. For convenience, some derived lsst.pex.config.Field-types (ConfigField and ConfigChoiceField) are defined in lsst.pex.config that handle recursing into subconfigs.

Inter-field relationships should only be checked in derived Config classes after calling this method, and base validation is complete.

values()

Get field values.

Returns:

valuesValuesView

Iterator of field values.