ordvec 0.4.0

Training-free ordinal & sign quantization for compressed vector retrieval

ordvec (Python)

Python bindings for ordvec — a training-free ordinal & sign vector-quantization library for compressed nearest-neighbour retrieval over high-dimensional embeddings. Pure-Rust core, zero system dependencies; SIMD-accelerated at runtime (AVX-512 / AVX2 / scalar).

import numpy as np
import ordvec

q = ordvec.RankQuant(1024, 2)          # 1024-dim, 2 bits/coord
q.add(np.random.randn(10_000, 1024).astype(np.float32))
# asymmetric: full-precision float queries vs bucketed docs (recommended)
scores, ids = q.search_asymmetric(np.random.randn(8, 1024).astype(np.float32), k=10)

Classes

Class	Purpose
Rank	Full-precision rank vectors (u16 per coordinate).
RankQuant	Bucketed ranks, bits ∈ {1, 2, 4}; symmetric + asymmetric (float-query LUT) scoring.
Bitmap	Constant-weight top-bucket bitmap per document; popcount(Q AND D) candidate scoring.
SignBitmap	Sign bitmap for sign-cosine candidate generation; separate from the constant-weight bitmap theorem.

Theory and calibration

Bitmap exposes the constant-weight top-bucket overlap statistic formalized in ordvec-formalization. In that finite Lean model, literal bitmap overlap is the query-preserving quotient statistic, an overlap threshold is Bayes-optimal under explicit monotone-overlap assumptions, and the idealized uniform constant-weight null calibrates that threshold by the hypergeometric upper tail.

This is not a deployment guarantee for every encoder or corpus. Real-corpus recall, monotonicity, and null fit remain empirical diagnostics.

Installation

pip install ordvec

Wheels target CPython 3.10+ (abi3) and require numpy>=2.2. Building from source needs a Rust toolchain (MSRV 1.89) and maturin.

Provenance & license

The ordvec Python bindings were developed within turbovec, factored out into this standalone package. turbovec (MIT, by Ryan Codrai) is credited as the origin project.

Dual-licensed under either of MIT or Apache-2.0 at your option.