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Announcing Python-Blosc2 3.3.0

We are introducing a new blosc2.transpose() function for natively transposing 2D NDArray instances, and a fast path for NDArray.slice() that delivers up to 40x speedup when slices align with underlying chunks. Documentation has also been improved with several edits throughout.

See benchmarks at: https://github.com/Blosc/python-blosc2/blob/main/bench/ndarray/aligned_chunks.py

You can think of Python-Blosc2 3.x as an extension of NumPy/numexpr that:

  • Can deal with ndarrays compressed using first-class codecs & filters.
  • Performs many kind of math expressions, including reductions, indexing...
  • Supports broadcasting operations.
  • Supports NumPy ufunc mechanism: mix and match NumPy and Blosc2 computations.
  • Integrates with Numba and Cython via UDFs (User Defined Functions).
  • Adheres to modern NumPy casting rules way better than numexpr.
  • Supports linear algebra operations (like blosc2.matmul()).

Install it with:

pip install blosc2 --update   # if you prefer wheels
conda install -c conda-forge python-blosc2 mkl  # if you prefer conda and MKL

For more info, you can have a look at the release notes in:

https://github.com/Blosc/python-blosc2/releases

Code example:

from time import time
import blosc2
import numpy as np

# Create some data operands
N = 20_000
a = blosc2.linspace(0, 1, N * N, dtype="float32", shape=(N, N))
b = blosc2.linspace(1, 2, N * N, shape=(N, N))
c = blosc2.linspace(-10, 10, N)  # broadcasting is supported

# Expression
t0 = time()
expr = ((a**3 + blosc2.sin(c * 2)) < b) & (c > 0)
print(f"Time to create expression: {time()-t0:.5f}")

# Evaluate while reducing (yep, reductions are in) along axis 1
t0 = time()
out = blosc2.sum(expr, axis=1)
t1 = time() - t0
print(f"Time to compute with Blosc2: {t1:.5f}")

# Evaluate using NumPy
na, nb, nc = a[:], b[:], c[:]
t0 = time()
nout = np.sum(((na**3 + np.sin(nc * 2)) < nb) & (nc > 0), axis=1)
t2 = time() - t0
print(f"Time to compute with NumPy: {t2:.5f}")
print(f"Speedup: {t2/t1:.2f}x")

assert np.all(out == nout)
print("All results are equal!")

This will output something like (using an Intel i9-13900X CPU here):

Time to create expression: 0.00033
Time to compute with Blosc2: 0.46387
Time to compute with NumPy: 2.57469
Speedup: 5.55x
All results are equal!

See a more in-depth example, explaining why Python-Blosc2 is so fast, at:

https://www.blosc.org/python-blosc2/getting_started/overview.html#operating-with-ndarrays

Sources repository

The sources and documentation are managed through github services at:

https://github.com/Blosc/python-blosc2

Python-Blosc2 is distributed using the BSD license, see https://github.com/Blosc/python-blosc2/blob/main/LICENSE.txt for details.

Mastodon feed

Follow https://fosstodon.org/@Blosc2 to get informed about the latest developments.

Enjoy!

  • Blosc Development Team Compress better, compute bigger