Compare https://stackoverflow.com/q/32954486/446149

benchmark_zip_equal_solutions.py

setup1 = """
from itertools import zip_longest

def zip_equal(*iterables):
    sentinel = object()
    for combo in zip_longest(*iterables, fillvalue=sentinel):
        if sentinel in combo:
            raise ValueError('Iterables have different lengths')
        yield combo

a = range(100)
b = range(100)
"""


setup2 = """
import itertools
class _SentinelException(Exception):
    def __iter__(self):
        raise _SentinelException


def zip_equal(iterable1, iterable2):
    i1 = iter(itertools.chain(iterable1, _SentinelException()))
    i2 = iter(iterable2)
    try:
        while True:
            yield (next(i1), next(i2))
    except _SentinelException:  # i1 reaches end
        try:
            next(i2)  # check whether i2 reaches end
        except StopIteration:
            pass
        else:
            raise ValueError('the second iterable is longer than the first one')
    except StopIteration: # i2 reaches end, as next(i1) has already been called, i1's length is bigger than i2
        raise ValueError('the first iterable is longger the second one.')

a = range(100)
b = range(100)
"""

import timeit
print(timeit.timeit('list(zip_equal(a, b))', setup1, number=100000)) # 1.55
print(timeit.timeit('list(zip_equal(a, b))', setup2, number=100000)) # 2.83