How do I use itertools.groupby()?

Question

I haven\'t been able to find an understandable explanation of how to actually use Python\'s itertools.groupby() function. What I\'m trying to do is this:

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Answer 1

You can write own groupby function:

           def groupby(data):
                kv = {}
                for k,v in data:
                    if k not in kv:
                         kv[k]=[v]
                    else:
                        kv[k].append(v)
           return kv

     Run on ipython:
       In [10]: data = [('a', 1), ('b',2),('a',2)]

        In [11]: groupby(data)
        Out[11]: {'a': [1, 2], 'b': [2]}