Is there any trick in order to easily transform a list to a dict with this specific format? I have been unable to do so.

FROM :

a = [
    ('A', 'B', 8),
    ('A', 'D', 10),
    ('A', 'E', 12),
    ('B', 'C', 6),
    ('B', 'F', 12),
    ('C', 'F', 8),
    ('D', 'E', 10),
    ('D', 'G', 30),
    ('E', 'F', 10),
    ('F', 'G', 12)
]

TO :

b = {
    "A": {"B": 8, "D": 10, "E": 12},
    "B": {"C": 6, "F": 12},
    "C": {"F": 8},
    "D": {"E": 10, "G": 30},
    "E": {"F": 10},
    "F": {"G": 12}
}

Thanks in advance you your tips

CodePudding user response：

Use defaultdict from collections module:

from collections import defaultdict

b = defaultdict(dict)
for k, k1, v in a:
    b[k].update({k1: v})

Output:

>>> b
defaultdict(dict,
            {'A': {'B': 8, 'D': 10, 'E': 12},
             'B': {'C': 6, 'F': 12},
             'C': {'F': 8},
             'D': {'E': 10, 'G': 30},
             'E': {'F': 10},
             'F': {'G': 12}})

An alternative version without defaultdict:

b = {}
for k, k1, v in a:
    t = b.setdefault(k, {})
    t[k1] = v

CodePudding user response：

loop the list, check if the key is in the dict. if it is then add to the dict of that key. if its not then create the keys dict:

a = [
    ('A', 'B', 8),
    ('A', 'D', 10),
    ('A', 'E', 12),
    ('B', 'C', 6),
    ('B', 'F', 12),
    ('C', 'F', 8),
    ('D', 'E', 10),
    ('D', 'G', 30),
    ('E', 'F', 10),
    ('F', 'G', 12)
]

final_list = {}
for item in a:
    if item[0] in final_list.keys():
        final_list[item[0]][item[1]] = item[2]
    else:
        final_list[item[0]] = {item[1]: item[2]}
print(final_list)

CodePudding user response：

If the first level keys are in grouped order, you can use groupby from itertools in a dictionary comprehension:

from itertools import groupby

d = { k:{c:n for _,c,n in v} for k,v in groupby(a,key=lambda t:t[0]) }

print(d)

{'A': {'B': 8, 'D': 10, 'E': 12}, 
 'B': {'C': 6, 'F': 12}, 
 'C': {'F': 8}, 
 'D': {'E': 10, 'G': 30}, 
 'E': {'F': 10}, 
 'F': {'G': 12}}

CodePudding user response：

Here's a beginner-friendly code.

1. We unpack the tuple and put the values in individual variables
2. If the key is already in dic, it means that a dictionary already exists and we simply add another pair.
3. Else, we make a new key value pair inside dic wherein the value is a dictionary.

list = [
    ('A', 'B', 8),
    ('A', 'D', 10),
    ('A', 'E', 12),
    ('B', 'C', 6),
    ('B', 'F', 12),
    ('C', 'F', 8),
    ('D', 'E', 10),
    ('D', 'G', 30),
    ('E', 'F', 10),
    ('F', 'G', 12)
]

dic = {}

for tuple in list:
    key, element, num = tuple
    if key in dic:
        dic[key][element] = num
    else:
        dic[key] = {element: num}

for k, v in dic.items():
    print(f"{k}: {v}")

Output:

{
    "A": {"B": 8, "D": 10, "E": 12},
    "B": {"C": 6, "F": 12},
    "C": {"F": 8},
    "D": {"E": 10, "G": 30},
    "E": {"F": 10},
    "F": {"G": 12}
}