FringeTask

class lsst.ip.isr.FringeTask(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

Task to remove fringes from a science exposure

We measure fringe amplitudes at random positions on the science exposure and at the same positions on the (potentially multiple) fringe frames and solve for the scales simultaneously.

Methods Summary

checkFilter(exposure) Check whether we should fringe-subtract the science exposure.
emptyMetadata() Empty (clear) the metadata for this Task and all sub-Tasks.
generatePositions(exposure, rng) Generate a random distribution of positions for measuring fringe amplitudes.
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.
loadFringes(fringeExp[, expId, assembler]) Pack the fringe data into a Struct.
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.
measureExposure(exposure, positions[, title]) Measure fringe amplitudes for an exposure
removePedestal(fringe) Remove pedestal from fringe exposure.
run(exposure, fringes[, seed]) Remove fringes from the provided science exposure.
solve(science, fringes) Solve for the scale factors with iterative clipping.
subtract(science, fringes, solution) Subtract the fringes.
timer(name, logLevel) Context manager to log performance data for an arbitrary block of code.

Methods Documentation

checkFilter(exposure)

Check whether we should fringe-subtract the science exposure.

Parameters:
exposure : lsst.afw.image.Exposure

Exposure to check the filter of.

Returns:
needsFringe : bool

If True, then the exposure has a filter listed in the configuration, and should have the fringe applied.

emptyMetadata() → None

Empty (clear) the metadata for this Task and all sub-Tasks.

generatePositions(exposure, rng)

Generate a random distribution of positions for measuring fringe amplitudes.

Parameters:
exposure : lsst.afw.image.Exposure

Exposure to measure the positions on.

rng : numpy.random.RandomState

Random number generator to use.

Returns:
positions : numpy.array

Two-dimensional array containing the positions to sample for fringe amplitudes.

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.

loadFringes(fringeExp, expId=None, assembler=None)

Pack the fringe data into a Struct.

This method moves the struct parsing code into a butler generation agnostic handler.

Parameters:
fringeExp : lsst.afw.exposure.Exposure

The exposure containing the fringe data.

expId : int, optional

Exposure id to be fringe corrected, used to set RNG seed.

assembler : lsst.ip.isr.AssembleCcdTask, optional

An instance of AssembleCcdTask (for assembling fringe frames).

Returns:
fringeData : pipeBase.Struct

Struct containing fringe data:

fringes

Calibration fringe files containing master fringe frames. ( : lsst.afw.image.Exposure or list thereof)

seed

Seed for random number generation. (int, optional)

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.

measureExposure(exposure, positions, title='Fringe')

Measure fringe amplitudes for an exposure

The fringe amplitudes are measured as the statistic within a square aperture. The statistic within a larger aperture are subtracted so as to remove the background.

Parameters:
exposure : lsst.afw.image.Exposure

Exposure to measure the positions on.

positions : numpy.array

Two-dimensional array containing the positions to sample for fringe amplitudes.

title : str, optional

Title used for debug out plots.

Returns:
fringes : numpy.array

Array of measured exposure values at each of the positions supplied.

removePedestal(fringe)

Remove pedestal from fringe exposure.

Parameters:
fringe : lsst.afw.image.Exposure

Fringe data to subtract the pedestal value from.

run(exposure, fringes, seed=None)

Remove fringes from the provided science exposure.

Primary method of FringeTask. Fringes are only subtracted if the science exposure has a filter listed in the configuration.

Parameters:
exposure : lsst.afw.image.Exposure

Science exposure from which to remove fringes.

fringes : lsst.afw.image.Exposure or list thereof

Calibration fringe files containing master fringe frames.

seed : int, optional

Seed for random number generation.

Returns:
solution : np.array

Fringe solution amplitudes for each input fringe frame.

rms : float

RMS error for the fit solution for this exposure.

solve(science, fringes)

Solve for the scale factors with iterative clipping.

Parameters:
science : numpy.array

Array of measured science image values at each of the positions supplied.

fringes : numpy.array

Array of measured fringe values at each of the positions supplied.

Returns:
solution : np.array

Fringe solution amplitudes for each input fringe frame.

rms : float

RMS error for the fit solution for this exposure.

subtract(science, fringes, solution)

Subtract the fringes.

Parameters:
science : lsst.afw.image.Exposure

Science exposure from which to remove fringes.

fringes : lsst.afw.image.Exposure or list thereof

Calibration fringe files containing master fringe frames.

solution : np.array

Fringe solution amplitudes for each input fringe frame.

Raises:
RuntimeError

Raised if the number of fringe frames does not match the number of measured amplitudes.

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