Latest recipes tagged "grouping"http://code.activestate.com/recipes/tags/grouping/new/2017-05-12T10:40:58-07:00ActiveState Code Recipesgroupby() For Unsorted Input (Python)
2017-05-12T10:40:58-07:00Alfehttp://code.activestate.com/recipes/users/4182236/http://code.activestate.com/recipes/580800-groupby-for-unsorted-input/
<p style="color: grey">
Python
recipe 580800
by <a href="/recipes/users/4182236/">Alfe</a>
(<a href="/recipes/tags/algorithm/">algorithm</a>, <a href="/recipes/tags/datastructures/">datastructures</a>, <a href="/recipes/tags/generators/">generators</a>, <a href="/recipes/tags/grouping/">grouping</a>, <a href="/recipes/tags/lazy/">lazy</a>).
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<p>We all know the <code>groupby()</code> which is available in the <code>itertools</code> standard module. This one yields groups of consecutive elements in the input which are meant to be together in one group. For non-consecutive elements this will yield more than one group for the same key.</p>
<p>So effectively, <code>groupby()</code> only reformats a flat list into bunches of elements from that list without reordering anything. In practice this means that for input sorted by key this works perfect, but for unsorted input it might yield several groups for the same key (with groups for other keys in between). Typically needed, though, is a grouping with reordering if necessary.</p>
<p>I implemented a likewise lazy function (yielding generators) which also accepts ungrouped input.</p>
Create PDF control break reports with itertools.groupby and xtopdf (Python)
2016-07-23T22:17:29-07:00Vasudev Ramhttp://code.activestate.com/recipes/users/4173351/http://code.activestate.com/recipes/580692-create-pdf-control-break-reports-with-itertoolsgro/
<p style="color: grey">
Python
recipe 580692
by <a href="/recipes/users/4173351/">Vasudev Ram</a>
(<a href="/recipes/tags/control/">control</a>, <a href="/recipes/tags/database/">database</a>, <a href="/recipes/tags/grouping/">grouping</a>, <a href="/recipes/tags/iterators/">iterators</a>, <a href="/recipes/tags/pdf/">pdf</a>, <a href="/recipes/tags/pdfwriter/">pdfwriter</a>, <a href="/recipes/tags/pdf_generation/">pdf_generation</a>, <a href="/recipes/tags/python/">python</a>, <a href="/recipes/tags/reportgeneration/">reportgeneration</a>, <a href="/recipes/tags/reporting/">reporting</a>, <a href="/recipes/tags/sql/">sql</a>, <a href="/recipes/tags/xtopdf/">xtopdf</a>).
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<p>This recipe shows how to create the classic control break style of report (a staple of data processing) using Python along with the groupby function from the itertools module, and xtopdf, a Python toolkit for PDF creation.</p>
Sublists (Python)
2010-12-21T16:28:20-08:00Michael Pucketthttp://code.activestate.com/recipes/users/4176295/http://code.activestate.com/recipes/577510-sublists/
<p style="color: grey">
Python
recipe 577510
by <a href="/recipes/users/4176295/">Michael Puckett</a>
(<a href="/recipes/tags/grouping/">grouping</a>, <a href="/recipes/tags/list/">list</a>, <a href="/recipes/tags/sublist/">sublist</a>).
</p>
<p>The opposite of list flattening. </p>
<p>Given a list and a length n return a list of sub lists of length n.</p>