http://code.activestate.com/recipes/tags/itertools/popular/2013-11-13T19:30:29-08:00ActiveState Code Recipes2013-11-13T19:30:29-08:00Jan Müllerhttp://code.activestate.com/recipes/users/4183984/http://code.activestate.com/recipes/578768-and-yet-another-round-robin-generator/

<p style="color: grey"> Python recipe 578768 by <a href="/recipes/users/4183984/">Jan Müller</a> (<a href="/recipes/tags/generator/">generator</a>, <a href="/recipes/tags/itertools/">itertools</a>, <a href="/recipes/tags/python/">python</a>, <a href="/recipes/tags/roundrobin/">roundrobin</a>). </p> <p>I know that there is a <a href="http://code.activestate.com/recipes/528936-roundrobin-generator/">nice recipe</a> already that even made it into the <a href="http://docs.python.org/2/library/itertools.html">Python documentation</a>, but this one is more concise and at the same time simpler.</p> <pre class="prettyprint"><code>&gt;&gt;&gt; list(roundrobin('ABC', 'D', 'EF')) ['A', 'D', 'E', 'B', 'F', 'C'] </code></pre>

2012-05-04T14:09:14-07:00John Crichtonhttp://code.activestate.com/recipes/users/4181975/http://code.activestate.com/recipes/578119-recursively-defined-haskell-style-infinite-lists/

<p style="color: grey"> Python recipe 578119 by <a href="/recipes/users/4181975/">John Crichton</a> (<a href="/recipes/tags/decorator/">decorator</a>, <a href="/recipes/tags/functional/">functional</a>, <a href="/recipes/tags/generator/">generator</a>, <a href="/recipes/tags/infinite/">infinite</a>, <a href="/recipes/tags/itertools/">itertools</a>, <a href="/recipes/tags/lazy/">lazy</a>, <a href="/recipes/tags/recursive/">recursive</a>). Revision 2. </p> <p>A decorator to simplify the creation of recursively defined, Haskell-style infinite lists -- ie. recursive generators -- inspired by Raymond Hettinger's "Technique for cyclical iteration" [*]. </p> <p>[*] <a href="http://code.activestate.com/recipes/576961-technique-for-cyclical-iteration/" rel="nofollow">http://code.activestate.com/recipes/576961-technique-for-cyclical-iteration/</a> </p>

2012-04-03T17:13:35-07:00Garretthttp://code.activestate.com/recipes/users/4181290/http://code.activestate.com/recipes/578092-flattening-an-arbitrarily-deep-list-or-any-iterato/

<p style="color: grey"> Python recipe 578092 by <a href="/recipes/users/4181290/">Garrett</a> (<a href="/recipes/tags/flatten/">flatten</a>, <a href="/recipes/tags/iterator/">iterator</a>, <a href="/recipes/tags/itertools/">itertools</a>, <a href="/recipes/tags/list/">list</a>, <a href="/recipes/tags/python/">python</a>, <a href="/recipes/tags/tuple/">tuple</a>). Revision 6. </p> <p>What if you had a list like this: [1, -10, [1,2,[3,4]], xrange(200)], and you just wanted to go through each element in order (wanted it to return a simple list of [1,-10,1,2,3,4,1,2,3,4...199])</p> <p>I've seen a couple of attempts to flatten arbitrarily deep lists. Many of them involve recursion, like this one: <a href="http://rightfootin.blogspot.com/2006/09/more-on-python-flatten.html" rel="nofollow">http://rightfootin.blogspot.com/2006/09/more-on-python-flatten.html</a></p> <p>Recursion is generally considered non-pythonic (at least to my knowledge), so I have used one which just involves simple iterators instead. Also, recursion will fail if the list is too deep (so it wouldn't really be arbitrary, would it?).</p>

2012-04-16T13:08:55-07:00Josh Bodehttp://code.activestate.com/recipes/users/4179046/http://code.activestate.com/recipes/577852-iterator-offsetter/

<p style="color: grey"> Python recipe 577852 by <a href="/recipes/users/4179046/">Josh Bode</a> (<a href="/recipes/tags/iterable/">iterable</a>, <a href="/recipes/tags/itertools/">itertools</a>, <a href="/recipes/tags/offset/">offset</a>). Revision 2. </p> <p>Produces a list of copies of an iterable that are offset by the supplied offsets.</p>

2011-06-23T16:36:38-07:00Andrew Dalkehttp://code.activestate.com/recipes/users/912777/http://code.activestate.com/recipes/577768-lazy-ordered-unique-elements-from-an-iterator/

<p style="color: grey"> Python recipe 577768 by <a href="/recipes/users/912777/">Andrew Dalke</a> (<a href="/recipes/tags/iterator/">iterator</a>, <a href="/recipes/tags/itertools/">itertools</a>, <a href="/recipes/tags/unique/">unique</a>). Revision 2. </p> <p>This implements a "unique" filter. Its input is an iterator of hashable items. It returns an iterator containing only the unique items of the input, in input order. That is, list(unique("cabbage")) produces ["c", "a", "b", "g"]. The implementation is lazy. The function supports the "key" parameter, which provides an alternate form of comparison.</p> <p>(Note: a better version of this is available from the itertools documentation as unique_everseen )</p>

2010-07-19T13:53:41-07:00Daniel Cohnhttp://code.activestate.com/recipes/users/4172918/http://code.activestate.com/recipes/577309-yet-another-roundrobin/

<p style="color: grey"> Python recipe 577309 by <a href="/recipes/users/4172918/">Daniel Cohn</a> (<a href="/recipes/tags/collections/">collections</a>, <a href="/recipes/tags/itertools/">itertools</a>, <a href="/recipes/tags/roundrobin/">roundrobin</a>). Revision 2. </p> <p>This recipe provides a decently simple implementation of a roundrobin using itertools and deque.</p>

2009-04-27T18:41:21-07:00marlonamorhttp://code.activestate.com/recipes/users/4169863/http://code.activestate.com/recipes/576719-flattened-list/

<p style="color: grey"> Python recipe 576719 by <a href="/recipes/users/4169863/">marlonamor</a> (<a href="/recipes/tags/flat/">flat</a>, <a href="/recipes/tags/generator/">generator</a>, <a href="/recipes/tags/itertools/">itertools</a>, <a href="/recipes/tags/list/">list</a>, <a href="/recipes/tags/nested/">nested</a>). Revision 2. </p> <p>This flattenizes any nested level list. I couln't find this in itertools module so I wrote it. Python 3 may be required.</p>