ImageReducer¶
- class lsst.ip.diffim.ImageReducer(config: Config | None = None, *, name: str | None = None, parentTask: Task | None = None, log: logging.Logger | lsst.utils.logging.LsstLogAdapter | None = None)¶
Bases:
Task
Base class for any ‘reduce’ task that is to be used as
ImageMapReduceConfig.reducer
.Basic reduce operations are provided by the
run
method of this class, to be selected by its config.Methods Summary
Empty (clear) the metadata for this Task and all sub-Tasks.
Get metadata for all tasks.
Get the task name as a hierarchical name including parent task names.
getName
()Get the name of the task.
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
(mapperResults, exposure, **kwargs)Reduce a list of items produced by
ImageMapper
.timer
(name[, logLevel])Context manager to log performance data for an arbitrary block of code.
Methods Documentation
- getFullMetadata() 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.
- metadata
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”.
- fullName
- getName() str ¶
Get the name of the task.
- Returns:
- taskName
str
Name of the task.
- taskName
See also
getFullName
Get the full name of the task.
- 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.
- taskDict
- classmethod makeField(doc: str) ConfigurableField ¶
Make a
lsst.pex.config.ConfigurableField
for this task.- Parameters:
- doc
str
Help text for the field.
- doc
- Returns:
- configurableField
lsst.pex.config.ConfigurableField
A
ConfigurableField
for this task.
- configurableField
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:
- 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
.
- name
Notes
The subtask must be defined by
Task.config.name
, an instance ofConfigurableField
orRegistryField
.
- run(mapperResults, exposure, **kwargs)¶
Reduce a list of items produced by
ImageMapper
.Either stitch the passed
mapperResults
list together into a new Exposure (default) or pass it through (ifself.config.reduceOperation
is ‘none’).If
self.config.reduceOperation
is not ‘none’, then expect that thepipeBase.Struct`s in the `mapperResults
list contain sub-exposures named ‘subExposure’, to be stitched back into a single Exposure with the same dimensions, PSF, and mask as the inputexposure
. Otherwise, themapperResults
list is simply returned directly.- Parameters:
- mapperResults
list
list of
lsst.pipe.base.Struct
returned byImageMapper.run
.- exposure
lsst.afw.image.Exposure
the original exposure which is cloned to use as the basis for the resulting exposure (if
self.config.mapper.reduceOperation
is not ‘None’)- kwargs
additional keyword arguments propagated from
ImageMapReduceTask.run
.
- mapperResults
- Returns:
- A
lsst.pipe.base.Struct
containing either anlsst.afw.image.Exposure
- (named ‘exposure’) or a list (named ‘result’),
- depending on
config.reduceOperation
.
- A
Notes
This currently correctly handles overlapping sub-exposures. For overlapping sub-exposures, use
config.reduceOperation='average'
.This correctly handles varying PSFs, constructing the resulting exposure’s PSF via CoaddPsf (DM-9629).
Known issues
To be done: correct handling of masks (nearly there)
This logic currently makes two copies of the original exposure (one here and one in
mapper.run()
). Possibly of concern for large images on memory-constrained systems.