List Files in a Snapshot

Lists all files in a dataset snapshot. Can list the root directory or drill into subdirectories using the tree parameter.

Usage

on_files(id, tag = NULL, tree = 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.

tree

Subdirectory token for listing nested files. Use the id column from a previous call to explore subdirectories. Default NULL lists the root directory.

client

An openneuro_client object. If NULL, creates a default client.

Value

A tibble with columns:

filename

Name of the file or directory

size

File size in bytes (numeric), may be NA for directories

directory

TRUE if this entry is a directory (logical)

annexed

TRUE if file is stored in git-annex (logical). Annexed files are typically larger and require special download handling.

id

Unique identifier for this entry. Pass it as the tree argument to explore a subdirectory.

urls

List column of direct HTTPS download URLs for the entry (character vector, empty for directories).

key

Backward-compatible alias of id (the directory tree token).

Returns an empty tibble with the same column structure if the snapshot has no files.

Details

OpenNeuro stores datasets using git-annex, where large files are stored separately from the git repository. The annexed column indicates which files use this storage method.

To explore a directory structure:

1. Call on_files() to get the root listing

2. Filter for directory == TRUE entries

3. Use the id from a directory to call on_files(tree = id)

See also

on_snapshots() to list available snapshots

Examples

if (FALSE) { # \dontrun{
# List root files using latest snapshot
files <- on_files("ds000001")
print(files)

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

# Explore a subdirectory
dirs <- files[files$directory, ]
if (nrow(dirs) > 0) {
  subfiles <- on_files("ds000001", tree = dirs$id[1])
  print(subfiles)
}

# Find all annexed (large) files
annexed_files <- files[files$annexed & !files$directory, ]
} # }