#!/usr/bin/env python
     #
     # Copyright 2007 Doug Hellmann.
     #
     #
     #                         All Rights Reserved
     #
     # Permission to use, copy, modify, and distribute this software and
     # its documentation for any purpose and without fee is hereby
     # granted, provided that the above copyright notice appear in all
     # copies and that both that copyright notice and this permission
     # notice appear in supporting documentation, and that the name of Doug
     # Hellmann not be used in advertising or publicity pertaining to
     # distribution of the software without specific, written prior
     # permission.
     #
     # DOUG HELLMANN DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
     # INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
     # NO EVENT SHALL DOUG HELLMANN BE LIABLE FOR ANY SPECIAL, INDIRECT OR
     # CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
     # OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
     # NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
     # CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     #
     
     """Grouping sequential values with groupby().
     
     """
     
     __version__ = "$Id$"
     #end_pymotw_header
     
     from itertools import *
     
     class Point:
         def __init__(self, x, y):
             self.x = x
             self.y = y
         def __repr__(self):
             return 'Point(%s, %s)' % (self.x, self.y)
         def __cmp__(self, other):
             return cmp((self.x, self.y), (other.x, other.y))
     
     # Create a dataset of Point instances
     data = list(imap(Point, 
                      cycle(islice(count(), 3)), 
                      islice(count(), 10),
                      )
                 )
     print 'Data:', data
     print
     
     # Try to group the unsorted data based on X values
     print 'Grouped, unsorted:'
     for k, g in groupby(data, lambda o:o.x):
         print k, list(g)
     print
     
     # Sort the data
     data.sort()
     print 'Sorted:', data
     print
     
     # Group the sorted data based on X values
     print 'Grouped, sorted:'
     for k, g in groupby(data, lambda o:o.x):
         print k, list(g)
     print