List Subjects in a Dataset — on_subjects • openneuro

Returns the subject IDs present in a dataset snapshot without downloading any data. This is a metadata-only query using the OpenNeuro GraphQL API.

Usage

on_subjects(id, tag = NULL, client = NULL)

Arguments

id: Dataset identifier (e.g., "ds000001").
tag: Snapshot version tag (e.g., "1.0.0"). If NULL (default), uses the most recent snapshot.
client: An openneuro_client object. If NULL, creates a default client.

Value

A tibble with columns:

dataset_id: The dataset identifier
subject_id: Subject identifier (e.g., "sub-01")
n_sessions: Number of sessions in the dataset (same for all rows)
n_files: Estimated files per subject (same for all rows)

Returns an empty tibble with the same column structure if the dataset has no BIDS subjects (e.g., non-BIDS datasets).

Details

Subject IDs are returned in natural sort order, so "sub-10" comes after "sub-9" rather than after "sub-1".

The n_sessions and n_files columns provide dataset-level context. Per-subject session and file counts are not available from the OpenNeuro API.

See also

on_files() to list files, on_download() to download data

Examples

if (FALSE) { # \dontrun{
# List subjects in a dataset
subjects <- on_subjects("ds000001")
print(subjects)

# List subjects in a specific snapshot
subjects <- on_subjects("ds000001", tag = "1.0.0")

# Get subject count
nrow(subjects)
} # }