DIG Open Data GWAS Access Module

Small, dependency-light helpers to open GWAS inputs as streaming text from local disk or the public DIG Open Data S3 registry.

Features

• Streaming text I/O (never loads full files into memory)
• Transparent gzip detection by magic number
• Pluggable storage backends (local disk + public S3 by default)
• No AWS credentials required for the DIG Open Data bucket

Install

This module uses only the Python standard library. If you want to package it:

python -m pip install -e .

If your environment blocks network access during build isolation, use:

python -m pip install -e . --no-build-isolation

R Package (digOpenData)

An R interface lives under r/digOpenData/ and follows Bioconductor-style conventions.

Quick usage (from inside the R package directory):

library(digOpenData)

list_ancestries()
list_traits(ancestry = "EU")

con <- open_trait("EU", "AlbInT2D")
lines <- read_trait_lines("EU", "AlbInT2D")

Quick Start

from dig_open_data import open_trait

with open_trait("EU", "AlbInT2D") as f:
    header = f.readline()
    for line in f:
        # parse line
        pass

Public API

• open_text(uri: str, *, encoding: str = "utf-8", retries: int = 3, download: bool = False, cache: CacheConfig | None = None, cache_refresh: bool = False) -> TextIO
• exists(uri: str) -> bool
• resolve_uri(uri: str) -> str
• register_backend(backend) -> None
• iter_lines(uri: str, *, encoding: str = "utf-8") -> Iterator[str]
• iter_tsv_dicts(uri: str, *, delimiter: str = "\t", encoding: str = "utf-8") -> Iterator[dict[str, str]]
• list_ancestries(*, bucket: str = DEFAULT_BUCKET, prefix: str = DEFAULT_PREFIX, max_keys: int = 1000) -> list[str]
• list_traits(*, bucket: str = DEFAULT_BUCKET, prefix: str = DEFAULT_PREFIX, ancestry: str | None = None, max_keys: int = 1000, limit: int | None = None, contains: str | None = None) -> list[str]
• list_files(*, bucket: str = DEFAULT_BUCKET, prefix: str = DEFAULT_PREFIX, max_keys: int = 1000, limit: int | None = None, ancestry: str | None = None, contains: str | None = None) -> list[str]
• list_dataset_files(*, bucket: str = DEFAULT_BUCKET, prefix: str = DEFAULT_PREFIX, max_keys: int = 1000, limit: int | None = None, ancestry: str | None = None, contains: str | None = None) -> list[str]
• list_files_with_metadata(*, bucket: str = DEFAULT_BUCKET, prefix: str = DEFAULT_PREFIX, ancestry: str | None = None, max_keys: int = 1000, limit: int | None = None, contains: str | None = None) -> list[FileEntry]
• build_key(ancestry: str, trait: str, *, prefix: str = DEFAULT_PREFIX, suffix: str = DEFAULT_SUFFIX) -> str
• open_trait(ancestry: str, trait: str, *, bucket: str = DEFAULT_BUCKET, prefix: str = DEFAULT_PREFIX, suffix: str = DEFAULT_SUFFIX, encoding: str = "utf-8", cache: CacheConfig | None = None) -> TextIO

Input Formats

This module is format-agnostic. It simply returns a streaming text handle. Downstream tools are expected to parse the file (TSV, CSV, etc.).

Dataset Discovery Utilities

You can list available files by ancestry and trait name, and retrieve documentation files stored alongside datasets.

from dig_open_data import list_ancestries, list_traits, list_files_with_metadata

ancestries = list_ancestries()
traits = list_traits(ancestry="EU")
entries = list_files_with_metadata(ancestry="EU")

for entry in entries:
    print(entry.ancestry, entry.trait, entry.key)

Notes:

• list_dataset_files() uses S3 ListObjectsV2 to return full object keys.

Tests

PYTHONPATH=src/dig_open_data/src ../.venv/bin/python -m unittest discover -s tests

CLI

You can run the CLI in two ways.

Option 1: Install (recommended for repeated use)

Install in editable mode, then use the dig-open-data command (NOTE: You might have to load a new tab or restart your terminal session):

python -m pip install -e .

List files under the default DIG prefix (bottom-line/):

dig-open-data list
dig-open-data list --limit 10
dig-open-data list --ancestry EU --json
dig-open-data list --contains T2D
dig-open-data list --max-keys 500

List available ancestries:

dig-open-data ancestries
dig-open-data ancestries --json
dig-open-data ancestries --max-keys 500

List available trait names:

dig-open-data traits
dig-open-data traits --ancestry EU --contains T2D
dig-open-data traits --json

Stream a file to stdout:

dig-open-data stream --ancestry EU --trait AlbInT2D | head
dig-open-data stream --file bottom-line/EU/AlbInT2D.sumstats.tsv.gz | head

Include ancestry + trait metadata in listings:

dig-open-data list --with-ancestry
dig-open-data list --with-ancestry --ancestry EU --limit 20

Option 2: No install (PYTHONPATH)

From the repo root:

PYTHONPATH=src ../.venv/bin/python -m dig_open_data.cli list
PYTHONPATH=src ../.venv/bin/python -m dig_open_data.cli list --with-ancestry
PYTHONPATH=src ../.venv/bin/python -m dig_open_data.cli ancestries
PYTHONPATH=src ../.venv/bin/python -m dig_open_data.cli traits --ancestry EU
PYTHONPATH=src ../.venv/bin/python -m dig_open_data.cli stream --ancestry EU --trait AlbInT2D | head

Listing Best Practices

• S3 ListObjectsV2 returns up to 1,000 keys per request, so large listings are paginated; this CLI paginates automatically but you should still use --limit to keep outputs manageable.
• Use --ancestry and --contains to scope listings to a smaller portion of the bucket.
• Dataset and ancestry discovery uses the S3 delimiter="/" behavior to return CommonPrefixes that act like subdirectories; this is why ancestry and dataset listings return prefixes rather than raw files.

Design Notes

• Gzip detection is based on the first two bytes (0x1f, 0x8b), not filename.
• S3 access uses unsigned HTTPS requests via urllib.request to avoid extra dependencies.
• Backends are intentionally minimal; add new schemes by registering a backend implementing the small protocol.
• open_text(..., retries=N) retries on truncated gzip streams by reopening and skipping already-read characters. Use download=True to stage remote files locally before reading.

Caching (Optional)

Caching is opt‑in. If you do nothing, behavior is unchanged (streaming reads).

Option 1: Explicit cache config (recommended)

from dig_open_data import CacheConfig, open_trait

cache = CacheConfig(dir="./data/dig_cache", max_bytes=10 * 1024**3, ttl_days=None)
with open_trait("EU", "AlbInT2D", cache=cache) as f:
    ...

Option 2: Environment variables (fallback)

Set at least DIG_OPEN_DATA_CACHE_DIR to enable caching. Other variables are optional.

export DIG_OPEN_DATA_CACHE_DIR=/data/dig_cache
export DIG_OPEN_DATA_CACHE_MAX_BYTES=10737418240  # 10GB
export DIG_OPEN_DATA_CACHE_TTL_DAYS=30

Env defaults:

• If DIG_OPEN_DATA_CACHE_DIR is not set, caching is disabled.
• If DIG_OPEN_DATA_CACHE_DIR is set:
  • DIG_OPEN_DATA_CACHE_MAX_BYTES defaults to 10GB if unset.
  • DIG_OPEN_DATA_CACHE_TTL_DAYS defaults to no TTL if unset.

If the environment variables are set, caching is enabled automatically even if your script doesn’t change.

Force refresh:

export DIG_OPEN_DATA_CACHE_FORCE=1

If set, cached entries are ignored and re-downloaded.

Eviction

The cache uses least‑recently‑used (LRU) eviction based on last access time. When the cache exceeds max_bytes, the oldest entries are removed first.