How do i sort nested dictionary based on value of first key

Question

I have a dictionary in following format:

{
 'Item1': {'Cl': ['E1', 'E2', 'E3'], 'Re': ['E1', 'E2', 'E3']}, 
 'Item2': {'Cl': ['E1', 'E2', 'E3'], 'Re': ['E1', 'E2', 'E3']}, 
 'Item3': {'Cl': ['E1', 'E2', 'E3'], 'Re': ['E1', 'E2', 'E3']},
 'Item4': {'Cl': ['E2', 'E1', 'E3'], 'Re': ['E1', 'E2', 'E3']}
 }

And i want to restructure in the following format:

{
 'Item1': {'Re': ['E1', 'E2', 'E3'], 'Cl': ['E1', 'E2', 'E3']}, 
 'Item2': {'Re': ['E1', 'E2', 'E3'], 'Cl': ['E1', 'E2', 'E3']}, 
 'Item3': {'Re': ['E1', 'E2', 'E3'], 'Cl': ['E1', 'E2', 'E3']},
 'Item4': {'Re': ['E2', 'E1', 'E3'], 'Cl': ['E1', 'E2', 'E3']}
     }

I have tried sorted() but it doesn't seem to work or maybe i'm not implementing it in the correct way.

Does it answer your question? https://stackoverflow.com/questions/9001509/how-can-i-sort-a-dictionary-by-key — Arkadiusz, Mar 22 '22 at 09:06
@mozway yeah. Basically for each item (Item1,Item2...) i want Re (and its values) before Cl. — Aaryan Singh, Mar 22 '22 at 09:13
Does this answer your question? [How can I sort a dictionary by key?](https://stackoverflow.com/questions/9001509/how-can-i-sort-a-dictionary-by-key) — mozway, Mar 22 '22 at 09:15
@Arkadiusz the dictionary being nested in my case is causing me issue — Aaryan Singh, Mar 22 '22 at 09:18
See also https://stackoverflow.com/questions/39980323/are-dictionaries-ordered-in-python-3-6 — Luatic, Mar 22 '22 at 09:39

score 1 · Accepted Answer · answered Mar 22 '22 at 09:19

1

You can use a dictionary comprehension. I am assuming here that you want to sort the keys by reverse lexicographic order:

{k:{k2:v[k2] for k2 in sorted(v, reverse=True)} for k,v in d.items()}

output:

{'Item1': {'Re': ['E1', 'E2', 'E3'], 'Cl': ['E1', 'E2', 'E3']},
 'Item2': {'Re': ['E1', 'E2', 'E3'], 'Cl': ['E1', 'E2', 'E3']},
 'Item3': {'Re': ['E1', 'E2', 'E3'], 'Cl': ['E1', 'E2', 'E3']},
 'Item4': {'Re': ['E1', 'E2', 'E3'], 'Cl': ['E2', 'E1', 'E3']}}

If you want to push 'Re' to the beginning, and keep the rest in the same order (assuming more than 2 keys), you could do:

{k:{k2:v[k2] for k2 in sorted(v, key='Re'.__ne__)} for k,v in d.items()}

answered Mar 22 '22 at 09:19

mozway

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Shouldn't this be using an `OrderedDict` or the like to guarantee that insertion order is remembered no matter the Python implementation? – Luatic Mar 22 '22 at 09:40
1

@LMD dictionaries are maintaining insertion order since python 3.7 ([part of spec](https://mail.python.org/pipermail/python-dev/2017-December/151283.html), not implementation detail) ;) – mozway Mar 22 '22 at 09:42

How do i sort nested dictionary based on value of first key

1 Answers1