python list of lists speed

speed_test.py

import random
import time

batch_size = 256 

def merge1(l):
    l = l / batch_size * batch_size
    manifest = range(0, l)
    batch_manifest = zip(*[iter(manifest)] * batch_size)
    start_time = time.time()
    result = list(sum(batch_manifest, ()))
    end_time = time.time()
    return end_time - start_time

def merge2(l):
    l = l / batch_size * batch_size
    manifest = range(0, l)
    batch_manifest = zip(*[iter(manifest)] * batch_size)
    start_time = time.time()
    result = [item for batch in batch_manifest for item in batch]
    '''
    for i in batch_manifest:
        for j in i:
            result.append(j)
    '''
    end_time = time.time()
    return end_time - start_time

def test():
    test_range = [1000, 10000, 100000, 1000000]
    for l in test_range:
        print 'merge2', l, merge2(l)
    for l in test_range:
        print 'merge1', l, merge1(l)

if __name__ == '__main__':
    test()