FringeTask¶

Bases: 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:

exposurelsst.afw.image.Exposure: Exposure to check the filter of.

Returns:

needsFringebool: 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:

exposurelsst.afw.image.Exposure: Exposure to measure the positions on.
rngnumpy.random.RandomState: Random number generator to use.

Returns:

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

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

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.

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:

fringeExplsst.afw.exposure.Exposure: The exposure containing the fringe data.
expIdint, optional: Exposure id to be fringe corrected, used to set RNG seed.
assemblerlsst.ip.isr.AssembleCcdTask, optional: An instance of AssembleCcdTask (for assembling fringe frames).

Returns:

fringeDatapipeBase.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) → 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.

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:

exposurelsst.afw.image.Exposure: Exposure to measure the positions on.
positionsnumpy.array: Two-dimensional array containing the positions to sample for fringe amplitudes.
titlestr, optional: Title used for debug out plots.

Returns:

fringesnumpy.array: Array of measured exposure values at each of the positions supplied.

removePedestal(fringe)¶

Remove pedestal from fringe exposure.

Parameters:

fringelsst.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:

exposurelsst.afw.image.Exposure: Science exposure from which to remove fringes.
fringeslsst.afw.image.Exposure or list thereof: Calibration fringe files containing master fringe frames.
seedint, optional: Seed for random number generation.

Returns:

solutionnp.array: Fringe solution amplitudes for each input fringe frame.
rmsfloat: RMS error for the fit solution for this exposure.

solve(science, fringes)¶

Solve for the scale factors with iterative clipping.

Parameters:

sciencenumpy.array: Array of measured science image values at each of the positions supplied.
fringesnumpy.array: Array of measured fringe values at each of the positions supplied.

Returns:

solutionnp.array: Fringe solution amplitudes for each input fringe frame.
rmsfloat: RMS error for the fit solution for this exposure.

subtract(science, fringes, solution)¶

Subtract the fringes.

Parameters:

sciencelsst.afw.image.Exposure: Science exposure from which to remove fringes.
fringeslsst.afw.image.Exposure or list thereof: Calibration fringe files containing master fringe frames.
solutionnp.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:

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

Navigation

FringeTask¶