ScaleZeroPointTask¶

class lsst.pipe.tasks.scaleZeroPoint.ScaleZeroPointTask(*args, **kwargs)¶

Bases: Task

Compute scale factor to scale exposures to a desired photometric zero point.

This simple version assumes that the zero point is spatially invariant.

Methods Summary

`computeImageScaler`(exposure[, dataRef])	Compute image scaling object for a given exposure.
`emptyMetadata`()	Empty (clear) the metadata for this Task and all sub-Tasks.
`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.
`getPhotoCalib`()	Get desired PhotoCalib.
`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[, dataRef])	Scale the specified exposure to the desired photometric zeropoint.
`scaleFromFluxMag0`(fluxMag0)	Compute the scale for the specified fluxMag0.
`scaleFromPhotoCalib`(calib)	Compute the scale for the specified PhotoCalib.
`timer`(name[, logLevel])	Context manager to log performance data for an arbitrary block of code.

Methods Documentation

computeImageScaler(exposure, dataRef=None)¶

Compute image scaling object for a given exposure.

Parameters:

exposurelsst.afw.image.Exposure: Exposure for which scaling is desired.
dataRefUnknown, optional: Data reference for exposure. Not used, but in API so that users can switch between spatially variant and invariant tasks.

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

getFullMetadata() → TaskMetadata¶

Get metadata for all tasks.

Returns:

metadataTaskMetadata: 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:

fullNamestr

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:

taskNamestr: Name of the task.

See also

getFullName

getPhotoCalib()¶

Get desired PhotoCalib.

Returns:

calibrationlsst.afw.image.PhotoCalib: Calibration with fluxMag0 set appropriately for config.zeroPoint.

getTaskDict() → Dict[str, ReferenceType[Task]]¶

Get a dictionary of all tasks as a shallow copy.

Returns:

taskDictdict: Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc.

classmethod makeField(doc: str) → ConfigurableField¶

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

Parameters:

docstr: Help text for the field.

Returns:

configurableFieldlsst.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: Any) → None¶

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

Parameters:

namestr

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, dataRef=None)¶

Scale the specified exposure to the desired photometric zeropoint.

Parameters:

exposurelsst.afw.image.Exposure: Exposure to scale; masked image is scaled in place.
dataRefUnknown: Data reference for exposure. Not used, but in API so that users can switch between spatially variant and invariant tasks.

Returns:

resultlsst.pipe.base.Struct

Results as a struct with attributes:

imageScaler: The image scaling object used to scale exposure.

scaleFromFluxMag0(fluxMag0)¶

Compute the scale for the specified fluxMag0.

This is a wrapper around scaleFromPhotoCalib, which see for more information.

Parameters:

fluxMag0float: Flux at magnitude zero.

Returns:

resultlsst.pipe.base.Struct

Results as a struct with attributes:

scale

Scale, such that if pixelCalib describes the photometric zeropoint of a pixel then the following scales that pixel to the photometric zeropoint specified by config.zeroPoint:

scale = computeScale(pixelCalib) pixel *= scale

scaleFromPhotoCalib(calib)¶

Compute the scale for the specified PhotoCalib.

Returns:

resultlsst.pipe.base.Struct

Results as a struct with attributes:

scale

Scale, such that if pixelCalib describes the photometric zeropoint of a pixel then the following scales that pixel to the photometric zeropoint specified by config.zeroPoint:

scale = computeScale(pixelCalib) pixel *= scale

Notes

Returns a struct to leave room for scaleErr in a future implementation.

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

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

Parameters:

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

Navigation

ScaleZeroPointTask¶