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(<type 'list'>, {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]}]

Answer 2

It's not fancy but it is simple

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 = dict((k, [i[0] for i in l if i[1] == k]) for k in frozenset(j[1] for j in l))

Huzzah!

Answer 3

for key, value in tuples:
    if d.get(key):
        d[key].append(value)
        continue
    d[key] =[value]

Answer 4

tuples = [(1,4),(2,4),(3,4),(4,15),(5,15),(6,23),(7,23),(8,23),(9,15),(10,23),(11,15),(12,15)]
dicts = {}
for elem in tuples:
    try:
        dicts[elem[1]].append(elem[0])
    except KeyError:
        dicts[elem[1]] = [elem[0],]

Answer 5

>>> a = [(1,4),(2,4),(3,4),(4,15),(5,15),(6,23),(7,23),(8,23),(9,15),(10,23),(11,15),(12,15)]
>>> b = {}
>>> for i, j in a:
...     b.setdefault(j, []).append(i)
...
>>> b
{23: [6, 7, 8, 10], 4: [1, 2, 3], 15: [4, 5, 9, 11, 12]}
>>>

Answer 6

This will do:

from collections import defaultdict

def to_list_of_dicts(list_of_tuples):
    d = defaultdict(list)
    for x, y in list_of_tuples:
        d[y].append(x)
    return sorted([{x: y} for (x, y) in d.items()])