Developer guide: Metadata

Metadata is non-annotation information about an asset. You can use metadata to search and filter your data rows in Labelbox. The metadata schema lives at the organization level. This allows you to apply the same metadata fields across multiple datasets.

There are two types of metadata: reserved fields (user cannot change) and custom (user-defined) fields.

Reserved fields

By default, Labelbox defines several metadata fields on your data rows. You don't have to use these fields; however, you cannot delete or rename these fields. (You can change the field values.)

Each metadata field has a unique schema ID used to upload data to Labelbox.

Name	Type
`tag`	Free text field
`split`	Enum - [train, valid, test]
`captureDateTime`	ISO 8601 datetime field. All times must be in UTC
`embedding`	A 128 length list 32 bit floats used for similarity search. All datarows share the same similarity index

Custom fields

All metadata is strictly typed. These are the custom fields Labelbox offers.

Type	Notes	Filtering
`DateTime`	An ISO 8601 datetime field. All times must be in UTC timezone	Equals, greater than, less than, between
`Number`	Floating-point value (max: 64-bit float)	Greater than & less than
`String`	free text field. Max 4,096 characters.	Equals & prefix matching
`Enum`	Enum field with options. Multiple options can be imported.	Equals
`Option (Enum)`	Option of an enum. Max 64 options can be created per Enum type. 128 for enterprise customers and can be further increased upon request.	Equals
`Embedding`	128 float 32 vector used for similarity

To view your metadata schema, go to the Schema tab and then select the Metadata subtab.

Create custom metadata schema via the UI

To create custom metadata fields via the UI, go to the Schema tab. Select Create.

Each metadata field must have a unique name and a type. The max number of fields per organization is determined by account tier.

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Metadata field limit
Know your account limits of maximum number of allowed metadata fields.

Once you create a field, you cannot change the type. You can modify the names of custom metadata schema by clicking the Edit button in the detail view of each schema. You cannot modify the names of reserved fields.

Bulk add metadata

Follow these steps to bulk add metadata to your data rows in Catalog.

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Limits
See this page to learn the limits for bulk adding metadata to data rows in Catalog.

Step 1: Select data rows

You will need to select a curate a subset of data.

For example, you may select a cluster of data from the projector view. Another option could be to select the top results of a natural language search. This way, you can use neural networks like CLIP as zero-shot classifiers. A third possibility is to select all assets that look similar to each other - thanks to Labelbox similarity search. Similarity search powered by embeddings allows you to leverage any off-the-shelf neural network as a zero-shot classifier.

There are three ways to select data rows:

Option 1: Select all filtered data rows by choosing Select all.
Option 2: Use the selection icon (checkbox) to manually select individual data rows.
Option 3: Bulk select data rows by selecting the first data row, press and hold Shift, and then select the last data row. All data rows between the first and last ones are selected.

In this example, we select all data rows containing the keyword "happy"

Step 2: Add metadata

After you select your data rows, select Add metadata from the selection menu.

Step 3: Pick a metadata field

From the selection menu, select the metadata field you want to apply.

You can search for metadata fields by typing their name if you don't see them in the dropdown.

Metadata fields must be exist in Labelbox beore they appear in the menu.

Step 4: Provide metadata values

Enter a metadata value. This metadata field and value will apply to all selected data rows.

Choose Save to apply the metadata in bulk. Changes can take time to be reflected in the data row metadata.

We tag all data rows that contain the keyword "happy" as: Sentiment > Positive — Here, all data rows containing the keyword "happy" are tagged as "Sentiment > Positive"

View metadata

You can surface data rows with the new metadata values, by searching on metadata in Labelbox.

We surface all data rows with the metadata field "Sentiment" and value "Positive" — Here, only data rows with the metadata field "Sentiment" and value "Positive" are displayed.

The newly created metadata tag will also show up in the detailed view.

Filter metadata

Once you upload your metadata, you can easily filter and view metadata in Catalog. If you want to label this set of data rows, you can filter by that metadata field and send them to a labeling project as a batch.

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Metadata viewing access
Labelers cannot filter and view metadata in Catalog. However, labelers will be able to view metadata information in the data row information panel.

Select a data row to open its detailed view. The Metadata panel shows all current metadata.

Export metadata

When you export your metadata, you can sync the newly created metadata with any outside system such as a cloud bucket, data lake, data warehouse, or database. To learn how to export data rows containing metadata, see Export from catalog.

Delete metadata

You can delete metadata for a data row through the SDK. Visit this guide for instructions.