Get a subset of a generator

Question

I have a generator function and want to get the first ten items from it; my first attempt was:

my_generator()[:10] 

This doesn't work because generators aren't subscriptable, as the error tells me. Right now I have worked around that with:

list(my_generator())[:10] 

This works since it converts the generator to a list; however, it's inefficient and defeats the point of having a generator. Is there some built-in, Pythonic equivalent of [:10] for generators?

Answer 1

import itertools  itertools.islice(mygenerator(), 10) 

itertools has a number of utilities for working with iterators. islice takes start, stop, and step arguments to slice an iterator just as you would slice a list.

Answer 2

to clarify the above comments:

from itertools import islice  def fib_gen():     a, b = 1, 1     while True:         yield a         a, b = b, a + b  assert [1, 1, 2, 3, 5] == list(islice(fib_gen(), 5))