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EventKind

What a stored entry in an event-based label row asserts from its frame onward. An event-based row (a continuous scene, see :attr:~encord.objects.LabelRowV2.is_event_based) stores sparse events at nanosecond offsets rather than labels on a frame grid:
  • "upsert": the object exists with this geometry until its next event. An untagged entry reads as an upsert.
  • "delete": the object does not exist until a later upsert. Carries placeholder geometry nobody reads.

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LabelUpsertEvent Objects

The object exists with this geometry from frame until its next event.

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LabelDeleteEvent Objects

The object does not exist from frame until a later upsert. A delete carries no geometry, there are no coordinates to read.

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LabelEvent

One stored event: narrow on kind, or with isinstance, to reach an upsert’s coordinates.

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resolve_event_at

The event holding over frame, or None where the object does not exist. Arguments:
  • events - The object’s events sorted by frame ascending.
  • frame - The frame to resolve.
Returns: The last upsert at or before frame, unless the last event at or before frame is a delete.

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check_events_terminated

Raise unless every stretch the events open is closed by a delete. A trailing upsert is a dangling stretch: the object is present from it with no end. The editor never writes one — an object running to the end of the timeline is closed on the frame after it — so it is not a layout the SDK stores or loads. Half-built objects are allowed to dangle in memory while a caller assembles them; this is checked at the two points where the row meets stored labels, parsing them and writing them back out. Arguments:
  • events - The object’s stored events, sorted by frame ascending.
  • object_hash - The object the events belong to, named in the error.
Raises:
  • LabelRowError - If the events end on an upsert.

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event_ranges

The closed ranges an object is present over. Each upsert following absence opens a range; the next delete closes it on the frame before itself. Every range is closed: an object that runs to the end of the timeline is terminated by a delete on the frame after it. Arguments:
  • events - The object’s events sorted by frame ascending.
Raises:
  • LabelRowError - If the events end on an upsert, leaving a range with no closing delete.

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events_intersect

Whether the object is present anywhere in [start, end] (both inclusive). Arguments:
  • events - The object’s events sorted by frame ascending.
  • start - First frame of the window.
  • end - Last frame of the window.
Raises:
  • LabelRowError - If the events end on an upsert, leaving a range with no closing delete.

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prune_dangling_deletes

Frames of delete events that terminate nothing. A delete is dangling when it is the first event or directly follows another delete. Arguments:
  • events - The object’s events sorted by frame ascending.