Popular recipes tagged "heapq" but not "priority_queue"http://code.activestate.com/recipes/tags/heapq-priority_queue/2011-07-25T23:42:21-07:00ActiveState Code Recipesasyncore scheduler (Python)
2011-07-25T23:42:21-07:00Giampaolo Rodolàhttp://code.activestate.com/recipes/users/4178764/http://code.activestate.com/recipes/577808-asyncore-scheduler/
<p style="color: grey">
Python
recipe 577808
by <a href="/recipes/users/4178764/">Giampaolo Rodolà</a>
(<a href="/recipes/tags/asynchronous/">asynchronous</a>, <a href="/recipes/tags/asyncore/">asyncore</a>, <a href="/recipes/tags/heapq/">heapq</a>, <a href="/recipes/tags/nonblocking/">nonblocking</a>, <a href="/recipes/tags/scheduler/">scheduler</a>, <a href="/recipes/tags/twisted/">twisted</a>).
Revision 5.
</p>
<p>The thing I miss mostly in asyncore is a system for calling a function after a certain amount of time without blocking. This is crucial for simple tasks such as disconnecting a peer after a certain time of inactivity or more advanced use cases such as <a href="http://code.google.com/p/pyftpdlib/source/browse/tags/release-0.6.0/pyftpdlib/ftpserver.py#1048">bandwidth throttling</a>.</p>
<p>This recipe was initially inspired by Twisted's internet.base.DelayedCall class:</p>
<p><a href="http://twistedmatrix.com/trac/browser/tags/last_vfs_and_web2/twisted/internet/base.py#L34" rel="nofollow">http://twistedmatrix.com/trac/browser/tags/last_vfs_and_web2/twisted/internet/base.py#L34</a></p>
<p>...then included into pyftpdlib:</p>
<p><a href="http://code.google.com/p/pyftpdlib/issues/detail?id=72" rel="nofollow">http://code.google.com/p/pyftpdlib/issues/detail?id=72</a></p>
<p>...and finally proposed for inclusion into asyncore:</p>
<p><a href="http://bugs.python.org/issue1641" rel="nofollow">http://bugs.python.org/issue1641</a></p>
Handling ties for top largest/smallest elements (Python)
2009-04-07T18:57:35-07:00George Sakkishttp://code.activestate.com/recipes/users/2591466/http://code.activestate.com/recipes/576712-handling-ties-for-top-largestsmallest-elements/
<p style="color: grey">
Python
recipe 576712
by <a href="/recipes/users/2591466/">George Sakkis</a>
(<a href="/recipes/tags/heapq/">heapq</a>, <a href="/recipes/tags/largest/">largest</a>, <a href="/recipes/tags/smallest/">smallest</a>, <a href="/recipes/tags/top/">top</a>).
Revision 8.
</p>
<p>The heapq module provides efficient functions for getting the top-N smallest and
largest elements of an iterable. A caveat of these functions is that if there
are ties (i.e. equal elements with respect to the comparison key), some elements
may end up in the returned top-N list while some equal others may not:</p>
<pre class="prettyprint"><code>>>> nsmallest(3, [4,3,-2,-3,2], key=abs)
[-2, 2, 3]
</code></pre>
<p>Although 3 and -3 are equal with respect to the key function, only one of them
is chosen to be returned. For several applications, an all-or-nothing approach
with respect to ties is preferable or even required.</p>
<p>A new optional boolean parameter 'ties' is proposed to accomodate these cases.
If ties=True and the iterable contains more than N elements, the length of the
returned sorted list can be lower than N if not all ties at the last position
can fit in the list:</p>
<pre class="prettyprint"><code>>>> nsmallest(3, [4,3,-2,-3,2], key=abs, ties=True)
[-2, 2]
</code></pre>