MatchOptimisticBTask

class lsst.meas.astrom.MatchOptimisticBTask(**kwargs)

Bases: lsst.pipe.base.Task

Match sources to reference objects using the Optimistic Pattern Matcher B algorithm of Tabur 2007.

Methods Summary

emptyMetadata()	Empty (clear) the metadata for this Task and all sub-Tasks.
filterStars(refCat)	Extra filtering pass; subclass if desired.
getAllSchemaCatalogs()	Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict.
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.
getSchemaCatalogs()	Get the schemas generated by this 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.
matchObjectsToSources(refCat, sourceCat, …)	Match sources to position reference stars.
timer(name[, logLevel])	Context manager to log performance data for an arbitrary block of code.

Methods Documentation

emptyMetadata()

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

filterStars(refCat)

Extra filtering pass; subclass if desired.

Parameters

refCatlsst.afw.table.SimpleCatalog

Catalog of reference objects.

Returns

trimmedRefCatlsst.afw.table.SimpleCatalog

Reference catalog with some filtering applied. Currently no filtering is applied.

getAllSchemaCatalogs()

Get schema catalogs for all tasks in the hierarchy, combining the results into a single dict.

Returns

schemacatalogsdict

Keys are butler dataset type, values are a empty catalog (an instance of the appropriate lsst.afw.table Catalog type) for all tasks in the hierarchy, from the top-level task down through all subtasks.

Notes

This method may be called on any task in the hierarchy; it will return the same answer, regardless.

The default implementation should always suffice. If your subtask uses schemas the override Task.getSchemaCatalogs, not this method.

getFullMetadata()

Get metadata for all tasks.

Returns

metadatalsst.daf.base.PropertySet

The PropertySet 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()

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()

Get the name of the task.

Returns

taskNamestr

Name of the task.

See also

getFullName

getSchemaCatalogs()

Get the schemas generated by this task.

Returns

schemaCatalogsdict

Keys are butler dataset type, values are an empty catalog (an instance of the appropriate lsst.afw.table Catalog type) for this task.

See also

Task.getAllSchemaCatalogs

Notes

Warning

Subclasses that use schemas must override this method. The default implemenation returns an empty dict.

This method may be called at any time after the Task is constructed, which means that all task schemas should be computed at construction time, not when data is actually processed. This reflects the philosophy that the schema should not depend on the data.

Returning catalogs rather than just schemas allows us to save e.g. slots for SourceCatalog as well.

getTaskDict()

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)

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("a brief description of what this task does")

makeSubtask(name, **keyArgs)

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 pex_config ConfigurableField or RegistryField.

matchObjectsToSources(refCat, sourceCat, wcs, sourceFluxField, refFluxField, match_tolerance=None)

Match sources to position reference stars.

Parameters

refCatlsst.afw.table.SimpleCatalog

Reference catalog to match.

sourceCatlsst.afw.table.SourceCatalog

Catalog of sources found on an exposure. This should already be down-selected to “good”/”usable” sources in the calling Task.

wcslsst.afw.geom.SkyWcs

Current WCS of the exposure containing the sources.

sourceFluxFieldstr

Field of the sourceCat to use for flux

refFluxFieldstr

Field of the refCat to use for flux

match_tolerancelsst.meas.astrom.MatchTolerance

Object containing information from previous lsst.meas.astrom.AstrometryTask match/fit cycles for use in matching. If None is config defaults.

Returns

matchResultlsst.pipe.base.Struct

Result struct with components

• matches : List of matches with distance below the maximum match distance (list of lsst.afw.table.ReferenceMatch).

• useableSourceCat : Catalog of sources matched and suited for WCS fitting (lsst.afw.table.SourceCatalog).

• match_tolerance : MatchTolerance object updated from this match iteration (lsst.meas.astrom.MatchTolerance).

timer(name, logLevel=10000)

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 lsst.log level constant.

See also

timer.logInfo

Examples

Creating a timer context:

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