Combine enumerate + itertools.izip in Python

Question

I would like to iterate + enumerate over two lists in Python. The following code looks ugly. Is there any better solution?

for id, elements in enumerate(itertools.izip(as, bs)):
  a = elements[0]
  b = elements[1]
  # do something with id, a and b

Thank you.

score 18 · Accepted Answer · answered Aug 18 '11 at 12:23

18

You can assign a and b during the for loop:

for id, (a, b) in enumerate(itertools.izip(as, bs)):
  # do something with id, a and b

answered Aug 18 '11 at 12:23

2

You can trust Python to have a nice and simple solution :). – Peter Collingridge Aug 18 '11 at 12:43

score 12 · Answer 2 · answered Aug 18 '11 at 12:26

12

You could use itertools.count instead of enumerate:

for id_, a, b in itertools.izip(itertools.count(), as_, bs):
  # do something with id_, a and b

Note that I've changed the variable names slightly to avoid a reserved word and the name of a builtin.

answered Aug 18 '11 at 12:26

Michael J. Barber

1

Nice change of variable names in accordance with PEP-8, bu using `itertools.count` over `enumerate` is not actually an improvement. – jamylak Jun 23 '13 at 10:52
IMHO it is an improvement, because you can use the `itertools.izip(itertools.count(), as_, bs)` experssion as an argument of `multiprocessing.pool.map_async()`, which is not convenient with the for loop. – user1898037 Jul 26 '17 at 14:28

2 Answers2