SubtractBackgroundTask¶

class lsst.meas.algorithms.SubtractBackgroundTask(config: Optional[Config] = None, name: Optional[str] = None, parentTask: Optional[Task] = None, log: Optional[Union[logging.Logger, lsst.utils.logging.LsstLogAdapter]] = None)¶

Bases: lsst.pipe.base.Task

Subtract the background from an exposure

Methods Summary

`emptyMetadata`()	Empty (clear) the metadata for this Task and all sub-Tasks.
`fitBackground`(maskedImage[, nx, ny, algorithm])	Estimate the background of a masked image
`getFullMetadata`()	Get metadata for all tasks.
`getFullName`()	Get the task name as a hierarchical name including parent task names.
`getName`()	Get the name of the task.
`getTaskDict`()	Get a dictionary of all tasks as a shallow copy.
`makeField`(doc)	Make a `lsst.pex.config.ConfigurableField` for this task.
`makeSubtask`(name, **keyArgs)	Create a subtask as a new instance as the `name` attribute of this task.
`run`(exposure[, background, stats, statsKeys])	Fit and subtract the background of an exposure.
`timer`(name, logLevel)	Context manager to log performance data for an arbitrary block of code.

Methods Documentation

emptyMetadata() → None¶: Empty (clear) the metadata for this Task and all sub-Tasks.

fitBackground(maskedImage, nx=0, ny=0, algorithm=None)¶

Estimate the background of a masked image

Parameters:	maskedImage : `lsst.afw.image.maskedImage` Masked image whose background is to be computed nx : ‘int` Number of x bands; if 0 compute from width and `self.config.binSizeX` ny : `int` Number of y bands; if 0 compute from height and `self.config.binSizeY` algorithm : `str` Name of interpolation algorithm; if None use `self.config.algorithm`
Returns:	bg : `lsst.afw.math.Background` A fit background
Raises:	RuntimeError Raised if lsst.afw.math.makeBackground returns None, an indicator of failure.

getFullMetadata() → lsst.pipe.base._task_metadata.TaskMetadata¶

Get metadata for all tasks.

Returns:	metadata : `TaskMetadata` The keys are the full task name. Values are metadata for the top-level task and all subtasks, sub-subtasks, etc.

Notes

The returned metadata includes timing information (if @timer.timeMethod is used) and any metadata set by the task. The name of each item consists of the full task name with . replaced by :, followed by . and the name of the item, e.g.:

topLevelTaskName:subtaskName:subsubtaskName.itemName

using : in the full task name disambiguates the rare situation that a task has a subtask and a metadata item with the same name.

getFullName() → str¶

Get the task name as a hierarchical name including parent task names.

Returns:	fullName : `str` The full name consists of the name of the parent task and each subtask separated by periods. For example: The full name of top-level task “top” is simply “top”. The full name of subtask “sub” of top-level task “top” is “top.sub”. The full name of subtask “sub2” of subtask “sub” of top-level task “top” is “top.sub.sub2”.

getName() → str¶

Get the name of the task.

Returns:	taskName : `str` Name of the task.

See also

getFullName

getTaskDict() → Dict[str, weakref.ReferenceType[lsst.pipe.base.task.Task]]¶

Get a dictionary of all tasks as a shallow copy.

Returns:	taskDict : `dict` Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc.

classmethod makeField(doc: str) → lsst.pex.config.configurableField.ConfigurableField¶

Make a lsst.pex.config.ConfigurableField for this task.

Parameters:	doc : `str` Help text for the field.
Returns:	configurableField : `lsst.pex.config.ConfigurableField` A `ConfigurableField` for this task.

Examples

Provides a convenient way to specify this task is a subtask of another task.

Here is an example of use:

class OtherTaskConfig(lsst.pex.config.Config):
    aSubtask = ATaskClass.makeField("brief description of task")

makeSubtask(name: str, **keyArgs) → None¶

Create a subtask as a new instance as the name attribute of this task.

Parameters:	name : `str` Brief name of the subtask. keyArgs Extra keyword arguments used to construct the task. The following arguments are automatically provided and cannot be overridden: “config”. “parentTask”.

Notes

The subtask must be defined by Task.config.name, an instance of ConfigurableField or RegistryField.

run(exposure, background=None, stats=True, statsKeys=None)¶

Fit and subtract the background of an exposure.

Parameters:

exposure : lsst.afw.image.Exposure: Exposure whose background is to be subtracted.
background : lsst.afw.math.BackgroundList: Initial background model already subtracted. May be None if no background has been subtracted.
stats : bool: If True then measure the mean and variance of the full background model and record the results in the exposure’s metadata.
statsKeys : tuple: Key names used to store the mean and variance of the background in the exposure’s metadata (another tuple); if None then use (“BGMEAN”, “BGVAR”); ignored if stats is false.

Returns:

background : lsst.afw.math.BackgroundLst: Full background model (initial model with changes), contained in an lsst.pipe.base.Struct.

timer(name: str, logLevel: int = 10) → Iterator[None]¶

Context manager to log performance data for an arbitrary block of code.

Parameters:	name : `str` Name of code being timed; data will be logged using item name: `Start` and `End`. logLevel A `logging` level constant.

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SubtractBackgroundTask¶