This is a great question. I’ll try to show you how we can use Python’s introspective abilities and open source to get an answer. We can use the dis module to peek behind the curtain and see how the CPython interpreter implements a for loop over an iterator. >>> def for_loop(iterable): … for item in … Read more
Why reinvent the wheel when you can use os.walk import os for root, dirs, files in os.walk(path): for name in files: print os.path.join(root, name) os.walk is a generator that yields the file names in a directory tree by walking the tree either top-down or bottom-up
import itertools class Indexable(object): def __init__(self,it): self.it = iter(it) def __iter__(self): return self.it def __getitem__(self,index): try: return next(itertools.islice(self.it,index,index+1)) except TypeError: return list(itertools.islice(self.it,index.start,index.stop,index.step)) You could use it like this: it = Indexable(fib()) print(it[10]) #144 print(it[2:12:2]) #[610, 1597, 4181, 10946, 28657] Notice that it[2:12:2] does not return [3, 8, 21, 55, 144] since the iterator had already … Read more
In general, the answer is itertools.islice, but you should note that islice doesn’t, and can’t, actually skip values. It just grabs and throws away start values before it starts yield-ing values. So it’s usually best to avoid islice if possible when you need to skip a lot of values and/or the values being skipped are … Read more
The range object is iterable. However, it’s not an iterator. To get an iterator, you need to call iter() first: >>> r=range(5,15) >>> next(iter(r)) 5 >>> next(iter(r)) 5 >>> next(iter(r)) 5 >>> next(iter(r)) 5 >>> i=iter(r) >>> next(i) 5 >>> next(i) 6 >>> next(i) 7 >>> next(i) 8 >>> iter(r) <range_iterator object at 0x10b0f0630> >>> … Read more
To the best of my knowledge (and I’ve looked, because I’ve wondered exactly the same thing), no: there is no direct way of doing this with the standard library. There is a thoroughly tested listify wrapper in unstdlib.py library, though: https://github.com/shazow/unstdlib.py/blob/master/unstdlib/standard/list_.py#L149 def listify(fn=None, wrapper=list): “”” A decorator which wraps a function’s return value in “list(…)“. … Read more
In Python 3.3+, you can use yield from. For example, >>> def get_squares(): … yield from (num ** 2 for num in range(10)) … >>> list(get_squares()) [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] It can actually be used with any iterable. For example, >>> def get_numbers(): … yield from range(10) … >>> … Read more
One short solution might be: let list = […sequenceGenerator(min, max)] Documentation on MDN
When you use send and expression yield in a generator, you’re treating it as a coroutine; a separate thread of execution that can run sequentially interleaved but not in parallel with its caller. When the caller executes R = m.send(a), it puts the object a into the generator’s input slot, transfers control to the generator, … Read more