ScaleZeroPointTask

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

Bases: lsst.pipe.base.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:
exposure : lsst.afw.image.Exposure

Exposure for which scaling is desired.

dataRef : Unknown, 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() → 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
getPhotoCalib()

Get desired PhotoCalib.

Returns:
calibration : lsst.afw.image.PhotoCalib

Calibration with fluxMag0 set appropriately for config.zeroPoint.

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, dataRef=None)

Scale the specified exposure to the desired photometric zeropoint.

Parameters:
exposure : lsst.afw.image.Exposure

Exposure to scale; masked image is scaled in place.

dataRef : Unknown

Data reference for exposure. Not used, but in API so that users can switch between spatially variant and invariant tasks.

Returns:
result : lsst.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:
fluxMag0 : float

Flux at magnitude zero.

Returns:
result : lsst.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:
result : lsst.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:
name : str

Name of code being timed; data will be logged using item name: Start and End.

logLevel

A logging level constant.

See also

timer.logInfo

Examples

Creating a timer context:

with self.timer("someCodeToTime"):
    pass  # code to time