Converting list of tuples into a dictionary

Question

I\'m looking for a way to convert a list of tuples like this:

[(1,4),(2,4),(3,4),(4,15),(5,15),(6,23),(7,23),(8,23),(9,15),(10,23),(11,15),(12,15)]
         


        

Answer 1

>>> from collections import defaultdict
>>> l= [(1,4),(2,4),(3,4),(4,15),(5,15),(6,23),(7,23),(8,23),(9,15),(10,23),(11,15),(12,15)]
>>> d= defaultdict( list )
>>> for v, k in l:
...     d[k].append(v)
... 
>>> d
defaultdict(, {23: [6, 7, 8, 10], 4: [1, 2, 3], 15: [4, 5, 9, 11, 12]})
>>> [ {k:d[k]} for k in sorted(d) ]
[{4: [1, 2, 3]}, {15: [4, 5, 9, 11, 12]}, {23: [6, 7, 8, 10]}]