Event Filtering¶

Generating filters explicitly¶

FilterEvents v1 reads and parses a mantid.api.ISplittersWorkspace object to generate a list of SplittingIntervals, which are used to split neutron events to specified output workspaces according to the times that they arrive detectors.

There can be two approaches to create a mantid.api.ISplittersWorkspace.

• GenerateEventsFilter v1 generate event filters by either by time or log value. The output filters are stored in a Splitters Workspace, which is taken as an input property of FilterEvents v1.
• Users can create a mantid.api.ISplittersWorkspace from scrach from Python script, because mantid.api.ISplittersWorkspace inherits from TableWorkspace.

Generating inexplicit filters¶

FilterByTime v1 and FilterByLogValue v1 generate event filters during execution.

• FilterByTime v1 generates a set of Splitting Interval according to user-specified setup for time splicing;
• FilterByLogValue v1 generates a set of Splitting Interval according to the value of a specific sample log.

GenerateEventsFilter v1 and FilterEvents v1 vs FilterByTime v1 and FilterByLogValue v1¶

• If GenerateEventsFilter v1 and FilterEvents v1 are set up correctly, they can have the same functionality as FilterByTime v1 and FilterByLogValue v1.
• FilterEvents v1 is able to filter neutron events by either their pulse times or their absolute times. An neutron event’s abolute time is the summation of its pulse time and TOF.
• FilterByLogValue v1 and FilterByTime v1 can only split neutron events by their pulse time.

Filtering by Splitting Interval¶

Splitting Interval is an individual class to indicate an independent time splitter. Any event can be filtered by a Splitting Interval object.

Splitters Workspace is a TableWorkspace that stors a set of Splitting Interval.

Filtering by duplicate entries/booleans¶

Duplicate entries in a TimeSeriesProperty and boolean type of TimeSeriesProperty are used in MantidPlot too to serve as time splitters.

These two are applied in the MantidPlot log viewing functionality and unfortunately intrudes into TimeSeriesProperty.

As time splitters are better to be isolated from logs, which are recorded in TimeSeriesProperty, it is not recommended to set up event filters by this approach.

Category: Concepts