With it, you can write faster and more memory efficient code that is often simpler and easier to read (although that is not always the case, as you saw in the section on second order recurrence relations ). batch.get(finelabels, None)) + assert labels is not None + for sample, label in itertools.izip(data. itertools is a powerful module in the Python standard library, and an essential tool to have in your toolkit. The 2to3 tool that ports Python 2 code to Python 3 will recognize this usage and leave the new builtins alone. diff -git a/python/paddle/v2/dataset/cifar.py. But that's something that needs looking in to. in this case, while a plain zip = izip may not be. For instance, I'm not 100% sure, but believe that the 2to3 tool will re-write zip correctly as list(zip(. These are used in various iterators to compute a fast and code efficient. The advantage of using future_builtin is that it's in effect a bit more "explicit" as to intended behaviour of the module, supported by the language syntax, and possibly recognised by tools. Python Itertools is a library in Python generally consisting of multiple methods. You do however then have the same problem of ImportError - so: try:įrom itertools import izip as zip # < 2.5 or 3.x FILE /usr/lib64/python2. I'd just like to add that using the map() function seems obsolete because list comprehensions do the same work in a more comprehensible (ha!) and faster manner.Not sure this is really an answer, or I should elaborate on my comment, and in hindsight probably not even a very good comment anyway, but:įirstly, you can just simplify it to: try:įrom 2.6 you can use as per the docs: from future_builtins import map # or zip or filter itertools is a built-in module no need to install it: Help on module itertools: NAME itertools - Functional tools for creating and using iterators. The iterable arguments may be a sequence or any iterable object the result is always a list. It works similarly to zip (), but returns an iterator instead of a list. If function is None, the identity function is assumed if there are multiple arguments, map() returns a list consisting of tuples containing the corresponding items from all iterables (a kind of transpose operation). Python provides the itertools package which provides convenience functions for many common iterator operations. izip () izip () returns an iterator that combines the elements of the passed iterators into tuples. If one iterable is shorter than another it is assumed to be extended with None items. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel. Why the change in name You might also notice that itertools.izip is now gone in Python 3 - that's because in Python 3, the zip built-in function now returns an iterator, whereas in Python 2 it returns a list. It should do the same as iziplongest from Python 2. If a function definition makes anything clear, it would look something like this:īut this is just simplifying since the map() function can process more than one iterable. 2to3 is a Python program that reads Python 2.x source code and applies a series of fixers to transform it into valid Python 3.x code. In Python 3's itertools there is a function called ziplongest. ) Apply function to every item of iterable and return a list of the results.
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