Deck 8: Tables (Annotations)

What function returns the built-in example SpatialData object used across several tutorials?

from spatialdata.datasets import blobs; sdata = blobs().

Can a Shapes or Points element be annotated directly, without a Table?

Yes → by simply adding extra columns to the GeoDataFrame/DataFrame.

Can a Labels element be annotated directly?

No → Labels have no natural per-instance row, so a Table is required.

How are a Labels element's instance indices identified?

Via get_element_instances(), which computes the unique non-zero pixel values.

Can Images be annotated by a Table at all?

No → Images have no index; but a table with no annotation target can still be used to annotate channel-level information.

Where exactly do a table's region, region_key, instance_key metadata live?

region_key and instance_key values live in two table.obs columns; the trio itself is recorded in table.uns["spatialdata_attrs"]

Is a table's own row index (not obs columns) ever used for the spatial link?

No → the region link relies entirely on the instance_key column's values, never the table's own index

What function returns (region, region_key, instance_key) for a table?

get_table_keys(table)

What function changes which element a table annotates?

sdata.set_table_annotates_spatialelement("table_name", region="new_element")

What does the match_rows argument control?

Whether output rows follow the SpatialElement's index order ("left") or the table's order ("right") → default is "no" (no reordering).

What join restriction applies specifically to Labels elements?

Only the left join is supported, with match_rows limited to no or left → because masking individual label pixels for other join types would be expensive.