Task

class lsst.pipe.base.Task(config: Config | None = None, *, name: str | None = None, parentTask: Task | None = None, log: logging.Logger | lsst.utils.logging.LsstLogAdapter | None = 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:

configTask.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()

namestr, optional

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

parentTaskTask-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.

loglogging.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

The constructor must use keyword parameters for everything other than the config parameter which can be positional or use keyword form.

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() → 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

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:

taskDictdict

Dictionary containing full task name: task object for the top-level task and all subtasks, sub-subtasks, etc.

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.

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.

logLevelint

A logging level constant.

See also

lsst.utils.timer.logInfo

Implementation function.

Examples

Creating a timer context:

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