# fiftyone.core.annotation.utils Annotation utils Copyright 2017-2026, Voxel51, Inc.
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**Functions:** | [`ensure_collection_is_supported`](#fiftyone.core.annotation.utils.ensure_collection_is_supported)(sample_collection) | Ensure a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection) is supported by the App for annotation. | |-------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | [`get_supported_app_annotation_fields`](#fiftyone.core.annotation.utils.get_supported_app_annotation_fields)(...) | Gets the supported App annotation fields for a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection). | | [`list_valid_annotation_fields`](#fiftyone.core.annotation.utils.list_valid_annotation_fields)(sample_collection) | Lists all valid annotation fields for a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection). | | [`backfill_instances_from_index`](#fiftyone.core.annotation.utils.backfill_instances_from_index)(sample_collection) | Populates the `instance` attribute from a legacy `index` attribute for any of the given track label fields that have `index` values but no `instance` values yet. | | [`flatten_fields`](#fiftyone.core.annotation.utils.flatten_fields)(collection, fields[, ...]) | Flattens embedded document fields into dot-separated paths. | | [`get_type`](#fiftyone.core.annotation.utils.get_type)(field) | Get the `type` of a field for a label schema | ### fiftyone.core.annotation.utils.ensure_collection_is_supported(sample_collection) Ensure a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection) is supported by the App for annotation. > Args: > : sample_collection: a > : [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection) ### fiftyone.core.annotation.utils.get_supported_app_annotation_fields(sample_collection) Gets the supported App annotation fields for a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection). Currently supported media types for the collection are `image` and `3d`. See [`fiftyone.core.collections.SampleCollection.media_type`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection.media_type) All supported primitive and `embedded.document` primitives are supported as documented in `generate_label_schemas()` The below [`fiftyone.core.labels.Label`](fiftyone.core.labels.md#fiftyone.core.labels.Label) types are also resolved. Supported `image` [`fiftyone.core.labels.Label`](fiftyone.core.labels.md#fiftyone.core.labels.Label) types are: : - `classification`: [`fiftyone.core.labels.Classification`](fiftyone.core.labels.md#fiftyone.core.labels.Classification) - `classifications`: [`fiftyone.core.labels.Classifications`](fiftyone.core.labels.md#fiftyone.core.labels.Classifications) - `detection`: [`fiftyone.core.labels.Detection`](fiftyone.core.labels.md#fiftyone.core.labels.Detection) - `detections`: [`fiftyone.core.labels.Detections`](fiftyone.core.labels.md#fiftyone.core.labels.Detections) Supported `3d` label types are: : - `classification`: [`fiftyone.core.labels.Classification`](fiftyone.core.labels.md#fiftyone.core.labels.Classification) - `classifications`: [`fiftyone.core.labels.Classifications`](fiftyone.core.labels.md#fiftyone.core.labels.Classifications) - `polyline`: [`fiftyone.core.labels.Polyline`](fiftyone.core.labels.md#fiftyone.core.labels.Polyline) - `polylines`: [`fiftyone.core.labels.Polylines`](fiftyone.core.labels.md#fiftyone.core.labels.Polylines) * **Parameters:** **sample_collection** – a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection) * **Returns:** a list of supported fields ### fiftyone.core.annotation.utils.list_valid_annotation_fields(sample_collection, require_app_support=False, flatten=False, include_frames=False) Lists all valid annotation fields for a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection). A field may be valid, but not yet supported by the App for human annotation. * **Parameters:** * **sample_collection** – a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection) * **require_app_support** (*False*) – whether to only include fields supported by the App for annotation * **flatten** (*False*) – whether to flatten embedded documents with `dot.notation` * **include_frames** (*False*) – whether to also include valid per-frame label fields, keyed by their `frames.` path * **Returns:** a sorted list of valid annotation field names ### fiftyone.core.annotation.utils.backfill_instances_from_index(sample_collection, fields=None) Populates the `instance` attribute from a legacy `index` attribute for any of the given track label fields that have `index` values but no `instance` values yet. Lets datasets whose tracks are defined by `index` (rather than `instance`) be recognized as tracks during a scan. Fields that already have any `instance` values are left untouched, so existing tracks are never clobbered and the operation is idempotent. * **Parameters:** * **sample_collection** – a [`fiftyone.core.collections.SampleCollection`](fiftyone.core.collections.md#fiftyone.core.collections.SampleCollection) * **fields** (*None*) – a field name or iterable of field names to process. By default, all valid annotation fields are processed, matching the all-fields scan in `generate_label_schemas()` ### fiftyone.core.annotation.utils.flatten_fields(collection, fields, require_app_support=False) Flattens embedded document fields into dot-separated paths. * **Parameters:** * **collection** – the sample collection * **fields** – iterable of field names to flatten * **require_app_support** (*False*) – whether to only include fields supported by the App for annotation * **Returns:** sorted list of flattened field names ### fiftyone.core.annotation.utils.get_type(field) Get the `type` of a field for a label schema * **Parameters:** **field** – the field instance * **Returns:** a label schema `type`