Task¶

class lsst.pipe.base.Task(config: Optional[Config] = None, name: Optional[str] = None, parentTask: Optional[Task] = None, log: Optional[Union[logging.Logger, lsst.utils.logging.LsstLogAdapter]] = None)¶

Bases: object

Base class for data processing tasks.

See Overview of the task framework to learn what tasks are, and Creating a task for more information about writing tasks.

Parameters:

config : Task.ConfigClass instance, optional

Configuration for this task (an instance of Task.ConfigClass, which is a task-specific subclass of lsst.pex.config.Config, or None. If None:

If parentTask specified then defaults to parentTask.config.<name>
If parentTask is None then defaults to self.ConfigClass()

name : str, optional

Brief name of task, or None; if None then defaults to Task._DefaultName

parentTask : Task-type, optional

The parent task of this subtask, if any.

If None (a top-level task) then you must specify config and name is ignored.
If not None (a subtask) then you must specify name.

log : logging.Logger or subclass, optional

Log whose name is used as a log name prefix, or None for no prefix. Ignored if is parentTask specified, in which case parentTask.log’s name is used as a prefix. The task’s log name is prefix + "." + name if a prefix exists, else name. The task’s log is then a child logger of parentTask.log (if parentTask specified), or a child logger of the log from the argument (if log is not None).

Raises:

RuntimeError

Raised under these circumstances:

If parentTask is None and config is None.
If parentTask is not None and name is None.
If name is None and _DefaultName does not exist.

Notes

Useful attributes include:

log: an logging.Logger or subclass.
config: task-specific configuration; an instance of ConfigClass (see below).
metadata: a TaskMetadata for collecting task-specific metadata, e.g. data quality and performance metrics. This is data that is only meant to be persisted, never to be used by the task.

Use a lsst.pipe.base.PipelineTask subclass to perform I/O with a Butler.

Subclasses must also have an attribute ConfigClass that is a subclass of lsst.pex.config.Config which configures the task. Subclasses should also have an attribute _DefaultName: the default name if there is no parent task. _DefaultName is required for subclasses of PipeLineTask and recommended for subclasses of Task because it simplifies construction (e.g. for unit tests).

Methods Summary

`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.
`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.
`timer`(name, logLevel)	Context manager to log performance data for an arbitrary block of code.

Methods Documentation

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

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.

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.

Navigation

Task¶