MatchBackgroundsConfig¶

class lsst.pipe.tasks.matchBackgrounds.MatchBackgroundsConfig¶

Bases: lsst.pex.config.Config

Attributes Summary

`approxWeighting`	Use inverse-variance weighting when approximating background offset model? This will fail when the background offset is constant (this is usually only the case in testing with artificial images).(usePolynomial=True) (`bool`, default `True`)
`badMaskPlanes`	Names of mask planes to ignore while estimating the background (`List`, default `['NO_DATA', 'DETECTED', 'DETECTED_NEGATIVE', 'SAT', 'BAD', 'INTRP', 'CR']`)
`bestRefWeightCoverage`	Weight given to coverage (number of pixels that overlap with patch), when calculating best reference exposure.
`bestRefWeightLevel`	Weight given to mean background level when calculating best reference exposure.
`bestRefWeightVariance`	Weight given to image variance when calculating best reference exposure.
`binSize`	Bin size for gridding the difference image and fitting a spatial model (`int`, default `256`)
`gridStatistic`	Type of statistic to estimate pixel value for the grid points (`str`, default `'MEAN'`)
`gridStdevEpsilon`	Tolerance on almost zero standard deviation in a background-offset grid bin.
`history`
`interpStyle`	Algorithm to interpolate the background values; ignored if usePolynomial is TrueMaps to an enum; see afw.math.Background (`str`, default `'AKIMA_SPLINE'`)
`numIter`	Number of iterations of outlier rejection; ignored if gridStatistic != ‘MEANCLIP’.
`numSigmaClip`	Sigma for outlier rejection; ignored if gridStatistic != ‘MEANCLIP’.
`order`	Order of Chebyshev polynomial background model.
`undersampleStyle`	Behaviour if there are too few points in grid for requested interpolation style.
`usePolynomial`	Fit background difference with Chebychev polynomial interpolation (using afw.math.Approximate)? If False, fit with spline interpolation using afw.math.Background (`bool`, default `False`)

Methods Summary

`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

approxWeighting¶: Use inverse-variance weighting when approximating background offset model? This will fail when the background offset is constant (this is usually only the case in testing with artificial images).(usePolynomial=True) (bool, default True)

badMaskPlanes¶: Names of mask planes to ignore while estimating the background (List, default ['NO_DATA', 'DETECTED', 'DETECTED_NEGATIVE', 'SAT', 'BAD', 'INTRP', 'CR'])

bestRefWeightCoverage¶

Weight given to coverage (number of pixels that overlap with patch), when calculating best reference exposure. Higher weight prefers exposures with high coverage.Ignored when reference visit is supplied (float, default 0.4)

Valid Range = [0.0,1.0)

bestRefWeightLevel¶

Weight given to mean background level when calculating best reference exposure. Higher weight prefers exposures with low mean background level. Ignored when reference visit is supplied. (float, default 0.2)

Valid Range = [0.0,1.0)

bestRefWeightVariance¶

Weight given to image variance when calculating best reference exposure. Higher weight prefers exposures with low image variance. Ignored when reference visit is supplied (float, default 0.4)

Valid Range = [0.0,1.0)

binSize¶: Bin size for gridding the difference image and fitting a spatial model (int, default 256)

gridStatistic¶

Type of statistic to estimate pixel value for the grid points (str, default 'MEAN')

Allowed values:

'MEAN': mean
'MEDIAN': median
'MEANCLIP': clipped mean
'None': Field is optional

gridStdevEpsilon¶

Tolerance on almost zero standard deviation in a background-offset grid bin. If all bins have a standard deviation below this value, the background offset model is approximated without inverse-variance weighting. (usePolynomial=True) (float, default 1e-08)

Valid Range = [0.0,inf)

history¶

interpStyle¶

Algorithm to interpolate the background values; ignored if usePolynomial is TrueMaps to an enum; see afw.math.Background (str, default 'AKIMA_SPLINE')

Allowed values:

'CONSTANT': Use a single constant value
'LINEAR': Use linear interpolation
'NATURAL_SPLINE': cubic spline with zero second derivative at endpoints
'AKIMA_SPLINE': higher-level nonlinear spline that is more robust to outliers
'NONE': No background estimation is to be attempted
'None': Field is optional

numIter¶: Number of iterations of outlier rejection; ignored if gridStatistic != ‘MEANCLIP’. (int, default 2)

numSigmaClip¶: Sigma for outlier rejection; ignored if gridStatistic != ‘MEANCLIP’. (int, default 3)

order¶: Order of Chebyshev polynomial background model. Ignored if usePolynomial False (int, default 8)

undersampleStyle¶

Behaviour if there are too few points in grid for requested interpolation style. Note: INCREASE_NXNYSAMPLE only allowed for usePolynomial=True. (str, default 'REDUCE_INTERP_ORDER')

Allowed values:

'THROW_EXCEPTION': throw an exception if there are too few points
'REDUCE_INTERP_ORDER': use an interpolation style with a lower order.
'INCREASE_NXNYSAMPLE': Increase the number of samples used to make the interpolation grid.
'None': Field is optional

usePolynomial¶: Fit background difference with Chebychev polynomial interpolation (using afw.math.Approximate)? If False, fit with spline interpolation using afw.math.Background (bool, default False)

Methods Documentation

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

Compare this configuration to another Config for equality.

Parameters:

other : lsst.pex.config.Config: Other Config object to compare against this config.
shortcut : bool, optional: If True, return as soon as an inequality is found. Default is True.
rtol : float, optional: Relative tolerance for floating point comparisons.
atol : float, optional: Absolute tolerance for floating point comparisons.
output : callable, optional: A callable that takes a string, used (possibly repeatedly) to report inequalities.

Returns:

isEqual : bool: 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:	name : `str` Name of a `Field` in this config. kwargs Keyword arguments passed to `lsst.pex.config.history.format`.
Returns:	history : `str` 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:	items : `dict_items` Iterator of tuples for each configuration. Tuple items are: Field name. Field value.

keys()¶

Get field names.

Returns:	names : `dict_keys` List of `lsst.pex.config.Field` names.

See also

lsst.pex.config.Config.iterkeys

load(filename, root='config')¶

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

Parameters:	filename : `str` Name of the configuration file. A configuration file is Python module. root : `str`, 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)¶

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

Parameters:

stream : file-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".

root : str, 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.

filename : str, optional

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

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)¶

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

Parameters:

code : str, bytes, or compiled string

Stream containing configuration override code.

root : str, 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.

filename : str, optional

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

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:	names : `list` of `str` Field names.

save(filename, root='config')¶

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

Parameters:	filename : `str` Desination filename of this configuration. root : `str`, 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:

outfile : file-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).
skipImports : bool, 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:	skipImports : `bool`, 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:	code : `str` 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:	values : `dict_values` Iterator of field values.

Navigation

MatchBackgroundsConfig¶