How do I optimize array access in python?

April 11, 2022

running time python my.py gets me 1.35s with the code below. Writing import py_compile, py_compile.compile('my.py', optimize=2) and running the file using time python __pycache__/my.cpython-310.opt-2.pyc gets me the same speed or slower. What can I do to speed this up?

import array
a = array.array('B')
for i in range(0, 1024*1024*10):
    a.append(i & 255)
print(str(len(a)))

>Solution :

Here are some possible options:

import timeit


def array():
    import array
    a = array.array('B')
    for i in range(0, 1024 * 1024 * 10):
        a.append(i & 255)
    print(str(len(a)))


def list_comprehension():
    a = [i & 255 for i in range(0, 1024 * 1024 * 10)]
    print(str(len(a)))


def numpy_array():
    import numpy as np
    a = np.arange(0, 1024 * 1024 * 10, dtype=np.uint8) & 255
    print(str(len(a)))


def numpy_array_repeat():
    import numpy as np
    a = np.tile(np.arange(0, 256, dtype=np.uint8), 4 * 1024 * 10 )
    print(str(len(a)))


print("array", timeit.timeit(array, number=5))
print("list_comprehension", timeit.timeit(list_comprehension, number=5))
print("numpy_array", timeit.timeit(numpy_array, number=5))
print("numpy_array_repeat", timeit.timeit(numpy_array_repeat, number=5))