Pure python implementation of product quantization for nearest neighbor search
Nano Product Quantization (nanopq): a vanilla implementation of Product Quantization (PQ) and Optimized Product Quantization (OPQ) written in pure python without any third party dependencies.
You can install the package via pip. This library works with Python 3.5+ on linux.
pip install nanopq
import nanopq
import numpy as np
N, Nt, D = 10000, 2000, 128
X = np.random.random((N, D)).astype(np.float32) # 10,000 128-dim vectors to be indexed
Xt = np.random.random((Nt, D)).astype(np.float32) # 2,000 128-dim vectors for training
query = np.random.random((D,)).astype(np.float32) # a 128-dim query vector
# Instantiate with M=8 sub-spaces
pq = nanopq.PQ(M=8)
# Train codewords
pq.fit(Xt)
# Encode to PQ-codes
X_code = pq.encode(X) # (10000, 8) with dtype=np.uint8
# Results: create a distance table online, and compute Asymmetric Distance to each PQ-code
dists = pq.dtable(query).adist(X_code) # (10000, )