itertools

When is it better to use zip instead of itertools.izip ? When you know you'll want the full list of items constructed (for instance, for passing to a function that would modify that list in-place). Or when you want to force the arguments you're passing to zip() to be completely evaluated at that specific point. zip computes all the list at once, izip computes the elements only when requested. One important difference is that 'zip' returns an actual list, 'izip' returns an 'izip object', which is not a list and does not support list-specific features (such as indexing): >>> l1 = [1, 2, 3, 4, 5,

I am trying to import the izip module like so: from itertools import izip However after recently changing over from Python 2.7 to 3 - it doesn't seem to work. I am trying to write to a csv file: writer.writerows(izip(variable1,2)) But I have no luck. Still encounter an error. In Python 3 the built-in zip does the same job as itertools.izip in 2.X(returns an iterator instead of a list). The zip implementation is almost completely copy-pasted from the old izip , just with a few names changed and pickle support added. Here is a benchmark between zip in Python 2 and 3 and izip in Python 2: Python