Bit packing speed tests: Numpy vs pure Python 3.

packbits_speed_test.py

#!/usr/bin/env python3

''' Test speeds of several bit packing algorithms 

    Written by PM 2Ring 2017.06.29
'''

import numpy as np
from timeit import Timer

def packbits_all(b):
    return int(''.join(map(str, b)), 2).to_bytes(-(-len(b) // 8), 'big')

def packbits_chunks(b):
    return bytes(int(u, 2) for u in map(''.join, zip(*[map(str, b)] * 8)))

def packbits_numpy(b):
    return np.packbits(b)

funcs = (
    packbits_all,
    packbits_chunks,
    packbits_numpy,
)

a = list(range(256))
print(a)
data = [int(v) for u in a for v in f'{u:08b}']

loops = 1 << 9
for i in range(8):
    size = len(data)
    print('\nSize: {}, Loops: {}'.format(size, loops))
    timings = []
    for func in funcs:
        name = func.__name__
        cmd = name + '(data)'
        setup = 'from __main__ import np, data, ' + name
        t = Timer(cmd, setup)
        result = sorted(t.repeat(3, loops))
        timings.append((result, name))
    timings.sort()
    for result, name in timings:
        print('{:15} : {}'.format(name, result))

    loops >>= 1
    data += data