Popular recipes tagged "iterable" but not "with_statement"

Numbers as Ranges - iterable integers (C++)

2014-10-02T12:13:52-07:00

C++ recipe 578945 by elazar (iterable, range). Revision 2.

This header file makes simple integers iterable. Note that it works only on C++11 or above.

Usage:

#include "num_range.h"
for (int i : 3) cout << i << endl;

Output: 0 1 2

Implementation note: This code is far too generic. We only need DerefableInt. The templates are there for no practical reason.

Cons: pollutes namespace std; nonstandard idiom;

Cycling a sequence (Python)

2014-09-20T19:20:46-07:00

Python recipe 578942 by Tomas Nordin (cyclic_iterator, generator, iterable, iterator, python).

A post-it function to cycle through some sequence. Better use itertools.cycle if for any iterable.

Truth Value Aware Iterable (Python)

2013-06-11T08:00:25-07:00

Python recipe 578549 by Alan Franzoni (boolean, iterable, truth).

This small recipe enables truth value testing on iterables.

It is quite common to do things like:

if somesequence:
    ...
else:
    ...

Such constructs, that enter the if block if the sequence's got one or more elements and the else block if it's empty, work fine on non-lazy builtin sequences (lists, strings, tuples) and dictionaries as well, but doesn't necessarily work on generic iterables - most of them are always true regardless of their contents, since they're some kind of object. A classical example is generators, but such behaviour can be extended to any object implementing the Iterable interface.

Just wrap your iterable with this decorator and you'll get a truth-aware iterable which supports proper truth testing by doing a small first element prefetching and can then be used just like the original iterable.

Iterator Offsetter (Python)

2012-04-16T13:08:55-07:00

Python recipe 577852 by Josh Bode (iterable, itertools, offset). Revision 2.

Produces a list of copies of an iterable that are offset by the supplied offsets.

Windowing an iterable with itertools (Python)

2010-04-15T18:45:41-07:00

Python recipe 577196 by Daniel Cohn (generator, iterable, iterator, loop, peeking, window).

Oftentimes a programmer needs to peek into an iterator without advancing it, a task for which many good solutions already exist. But what if the intrepid coder needs a fast and pythonic way to 'window' the data? This recipe demonstrates how to wrap any iterable with a class that adds two methods, prev and peek.