python - generator vs list

py-generator-list.py

# -*- coding: utf-8 -*-                                               |    N      Function             Runtime
                                                                      |    -----------------------------------------
import time                                                           |    1e+00  createGenerator      0.00000000 s
                                                                      |    1e+00  createGeneratorExp   0.00000000 s
def createGenerator(N):                                               |    1e+00  createList           0.00000000 s
    for i in range(N):                                                |    -----------------------------------------
        yield i * i                                                   |    1e+01  createGenerator      0.00000000 s
                                                                      |    1e+01  createGeneratorExp   0.00000000 s
def createGeneratorExp(N):                                            |    1e+01  createList           0.00000000 s
    return (i * i for i in range(N))                                  |    -----------------------------------------
                                                                      |    1e+02  createGenerator      0.00000000 s
def createList(N):                                                    |    1e+02  createGeneratorExp   0.00000000 s
    return [i * i for i in range(N)]                                  |    1e+02  createList           0.00000000 s
                                                                      |    -----------------------------------------
def test(fun, N):                                                     |    1e+03  createGenerator      0.00000000 s
    start = time.time()                                               |    1e+03  createGeneratorExp   0.00000000 s
    gen = fun(N)                                                      |    1e+03  createList           0.00000000 s
    for i in gen:                                                     |    -----------------------------------------
        pass                                                          |    1e+04  createGenerator      0.00000000 s
    end = time.time()                                                 |    1e+04  createGeneratorExp   0.01560640 s
    print('%-7.0e%-20s%- 2.8f s' % (N, fun.__name__, end - start))    |    1e+04  createList           0.00000000 s
                                                                      |    -----------------------------------------
print('%-7s%-20s %s' % ("N", "Function", "Runtime"))                  |    1e+05  createGenerator      0.00000000 s
print('-----------------------------------------')                    |    1e+05  createGeneratorExp   0.01562309 s
for Ni in range(9):                                                   |    1e+05  createList           0.01562333 s
    N = 10 ** Ni                                                      |    -----------------------------------------
    test(createGenerator, N)                                          |    1e+06  createGenerator      0.09379315 s
    test(createGeneratorExp, N)                                       |    1e+06  createGeneratorExp   0.09372592 s
    test(createList, N)                                               |    1e+06  createList           0.11374307 s
    print('-----------------------------------------')                |    -----------------------------------------
                                                                      |    1e+07  createGenerator      0.92200398 s
                                                                      |    1e+07  createGeneratorExp   1.01695776 s
                                                                      |    1e+07  createList           1.02991676 s
                                                                      |    -----------------------------------------
                                                                      |    1e+08  createGenerator      9.18688107 s
                                                                      |    1e+08  createGeneratorExp   9.20074868 s
                                                                      |    1e+08  createList           11.08157372 s
                                                                      |    -----------------------------------------