cython and indexing

1results.txt

test1: 0.08422580
test2: 0.06810107
test3: 0.04625974
test4: 0.04655976
test5: 0.00176943
test6: 0.00161580
test7: 0.00752258
test8: 0.07144928

dotest.py

import timeit
from test import *

num = 1000000

def test1(num):
    a = [0] * num
    for x in range(num):
        a[x] = x


print("test1: %.8f" % timeit.timeit("t.test1(t.num)", "import __main__ as t", number=1))
print("test2: %.8f" % timeit.timeit("t.test2(t.num)", "import __main__ as t", number=1))
print("test3: %.8f" % timeit.timeit("t.test3(t.num)", "import __main__ as t", number=1))
print("test4: %.8f" % timeit.timeit("t.test4(t.num)", "import __main__ as t", number=1))
print("test5: %.8f" % timeit.timeit("t.test5(t.num)", "import __main__ as t", number=1))
print("test6: %.8f" % timeit.timeit("t.test6(t.num)", "import __main__ as t", number=1))
test7(num)
test8(num)

test.pyx

from libc.stdlib cimport malloc, free
cimport cython
import time

cdef class DataType:
    cdef int data

def test2(num):
    a = [0] * num
    for x in range(num):
        a[x] = x

def test3(int num):
    cdef list a = [0] * num
    cdef int x
    for x in range(num):
        a[x] = x

cpdef test4(int num):
    cdef list a = [0] * num
    cdef int x
    for x in range(num):
        a[x] = x

cpdef int test5(int num) nogil:
    cdef int* m = <int*> malloc(sizeof(int) * num)
    cdef int[:] a 
    with cython.gil:
        a = <int[:num]> m
    cdef int x
    for x in range(num):
        a[x] = x
    free(m)

cpdef int test6(int num) nogil:
    cdef int* m = <int*> malloc(sizeof(int) * num)
    cdef int[:] a 
    with cython.gil:
        a = <int[:num]> m
    cdef int x
    # Actually bounds-checks seem very efficient
    with cython.boundscheck(False):
        for x in range(num):
            a[x] = x
    free(m)

cpdef int test7(int num) except -1:
    cdef list a = [0] * num
    cdef DataType t
    cdef int x
    for x in range(num):
        t = DataType()
        a[x] = t
    # Creating a python object is rather slow, lets assume they are pre-created
    start = time.time()
    for x in range(num):
        t = a[x]
        t.data = x
    end = time.time()
    print("test7: %.8f" % (end - start))

cpdef int test8(int num) except -1:
    start = time.time()
    cdef list a = [0] * num
    cdef DataType t
    cdef int x
    for x in range(num):
        t = DataType()
        t.data = x
        a[x] = t
    end = time.time()
    print("test8: %.8f" % (end - start))

xrun.sh

cythonize -i test.pyx; python dotest.py