# fiftyone.core.selection Exact episode and segment membership shared by selections and saved subsets. Copyright 2017-2026, Voxel51, Inc.
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**Functions:** | [`normalize_members`](#fiftyone.core.selection.normalize_members)(members) | Validates and deduplicates members without merging overlapping ranges. | |----------------------------------------------------------------------------------------|--------------------------------------------------------------------------| | [`member_key`](#fiftyone.core.selection.member_key)(member) | Returns a canonical identity excluding provenance and dataset scope. | | [`intersect_members`](#fiftyone.core.selection.intersect_members)(candidates, allowed) | Clips candidates to an explicit subset boundary on time and streams. | | [`select_parents`](#fiftyone.core.selection.select_parents)(collection, ids) | Selects parents by id, reaching into every slice of a grouped dataset. | | [`group_members`](#fiftyone.core.selection.group_members)(members[, samples]) | Groups stored members without changing full/segment coexistence. | | [`count_members`](#fiftyone.core.selection.count_members)(members[, unavailable_ids]) | Counts parent episodes separately from full-episode and segment units. | ### fiftyone.core.selection.normalize_members(members) Validates and deduplicates members without merging overlapping ranges. Bounds are decimal integers on a named native timebase. Frame events use zero-based, half-open sequence bounds; nanosecond sources retain their exact integer precision. Stream sets are resolved before capture. * **Parameters:** **members** – an iterable of episode/segment dictionaries * **Returns:** the normalized members, with combined provenance for duplicates ### fiftyone.core.selection.member_key(member) Returns a canonical identity excluding provenance and dataset scope. Storage always pairs this identity with a dataset ID and subset ID. ### fiftyone.core.selection.intersect_members(candidates, allowed) Clips candidates to an explicit subset boundary on time and streams. Whole-episode membership admits either scope. Segment-only membership cannot admit a full-episode candidate. Distinct saved intervals remain distinct even when overlapping. ### fiftyone.core.selection.select_parents(collection, ids) Selects parents by id, reaching into every slice of a grouped dataset. ### fiftyone.core.selection.group_members(members, samples=None) Groups stored members without changing full/segment coexistence. ### fiftyone.core.selection.count_members(members, unavailable_ids=()) Counts parent episodes separately from full-episode and segment units.