Hi Anand,vijay, and others, we have python 2.4.3 at our workplace and defaultdict is not present in the collections module in this python version.
>>> dir(collections) ['__doc__', '__file__', '__name__', 'deque'] >>> Also, could u suggest some way to tackle the following problem: Given: l = [['NM100', 1, 3], ['NM100', 7, 10], ['NM200', 13, 16]] want something like: z = [['NM100',[1,2,3,7,8,9,10]],['NM200',[13,14,15,16]]] On Tue, 27 Jul 2010 15:33:00 +0530 wrote >On Tue, Jul 27, 2010 at 3:16 PM, Anand Balachandran Pillai < abpil...@gmail.com> wrote: > > > On Tue, Jul 27, 2010 at 2:29 PM, Shekhar Tiwatne wrote: > >> On Tuesday 27 July 2010 12:18 PM, Vikram wrote: >> >>> have the following: >>> >>> >>> >>>> x >>>>>> >>>>>> >>>>> [['NM100', 1, 2], ['NM100', 3, 4], ['NM200', 5, 6]] >>> >>> >>>> for i in x: >>>>>> >>>>>> >>>>> ... print i >>> ... >>> ['NM100', 1, 2] >>> ['NM100', 3, 4] >>> ['NM200', 5, 6] >>> >>> ------ >>> how does one obtain list z such that >>> >>> z = [['NM100',1,2,3,4],['NM200',5,6]] >>> >> > This problem begs for the use of collections.defaultdict class. > > All the other solutions are ok, but defaultdict is meant to solve > problems like this. > > Here is the solution. > > >>> import collections > >>> l=[['NM100', 1, 2], ['NM100', 3, 4], ['NM200', 5, 6]] > >>> l2=[[x[0], x[1:]] for x in l] > >>> d = collections.defaultdict(list) > >>> for k, v in l2: d[k].extend(v) > >>> [[k, v] for k,v in d.iteritems()] > [['NM100', [1, 2, 3, 4]], ['NM200', [5, 6]]] > > What you want are the elements of the final list. > I didn't notice you want z = [['NM100',1,2,3,4],['NM200',5,6]] rather than, z= [['NM100', [1, 2, 3, 4]], ['NM200', [5, 6]]] So replace last line with, >>> [[k] + v for k,v in d.iteritems()] [['NM100', 1, 2, 3, 4], ['NM200', 5, 6]] > --Anand > > > > -- --Anand _______________________________________________ BangPypers mailing list BangPypers@python.org http://mail.python.org/mailman/listinfo/bangpypers _______________________________________________ BangPypers mailing list BangPypers@python.org http://mail.python.org/mailman/listinfo/bangpypers
