itar 0.3.0

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itar

itar builds constant‑time indexes over one or more tar file shards, enabling direct, random access to members without extracting the archives. It ships a lightweight CLI (itar) and a Python API.

Designed for large datasets and deep‑learning pipelines, it supports single or sharded tar archives with thread‑safe access for concurrent reads.

Quickstart (single tarball)

echo "Hello world!" > hello.txt
tar cf hello.tar hello.txt       # regular tarball
itar index create hello.itar     # indexes hello.tar
itar index list hello.itar       # list indexed members

import itar

with itar.open("hello.itar") as archive:
    print(archive["hello.txt"].read())

# If you just need the index dictionary without opening handles:
index = itar.index.build("hello.tar")
# Write the index file to disk:
itar.index.save("hello.itar", num_shards=None, index=index)

Quickstart (sharded tarballs)

Give each shard a zero-padded suffix before building the index:

tar cf photos-0.tar wedding/   # shard 0
tar cf photos-1.tar vacation/  # shard 1
itar index create photos.itar  # discovers photos-0.tar, photos-1.tar, ...
itar index list -l photos.itar # shard index, offsets, byte sizes

import itar

with itar.open("photos.itar") as photos:
    assert "wedding/cake.jpg" in photos
    img_bytes = photos["vacation/sunrise.jpg"].read()

index = itar.index.build(["photos-0.tar", "photos-1.tar"])
itar.index.create("photos.itar", ["photos-0.tar", "photos-1.tar"])

num_shards, stored_index = itar.index.load("photos.itar")

CLI reference

Command	Purpose
itar index create <archive>.itar [--single TAR | --shards shard0.tar shard1.tar ...]	Indexes a single archive or an explicit set of shards. With no flags, shards are auto-discovered next to <archive>.itar.
itar index list <archive>.itar	Lists members. Use -l for shard/offset info and -H for human-readable sizes.
itar index check <archive>.itar	Validates recorded entries; add --member NAME to focus on specific files.
itar cat <archive>.itar <member>	Streams a member’s bytes to stdout.

Python helpers

• itar.index.build(shards, progress_bar=False) -> dict: construct an index mapping for paths, file objects, or buffers.
• itar.index.create("archive.itar", shards): convenience wrapper that builds + saves an index file.
• itar.index.save(path, num_shards, index): serialize an index you built elsewhere.
• itar.index.load(path) -> (num_shards, index): load the msgpack index without opening shards.
• itar.open(path, *, shards=None, open_fn=None) -> IndexedTarFile: attach shard handles using an existing index file.