Ascending order sorting in list of dict

Question

How can I sort a list in ascending order without key matching?

Every key is unique and need sorting keys.

Input:

[{23: (1, 5)}, 
{59: (2, 3)}, 
{45: (2, 9)}, 
{28: (3, 6)}]

The output should be like this (Sorting based on keys of dict):

[{23: (1, 5)}, 
{28: (3, 6)},
{45: (2, 9)},
{59: (2, 3)}]

I don't understand your question. what are you trying to say @ScottHunter — Muhammad Haseeb Khan, Dec 14 '17 at 17:58
What if you had a dictionary with 2 keys? For example: `{1:(1,1), 99:(1,1)}`. Where should this appear in your sorted list? — Scott Hunter, Dec 14 '17 at 18:00
Why don't you put your data like `{23: (1, 5), 59: (2, 3)}` etc. sorting can be done after and an OrderedDict can be used if you need a dict like structure — Chris_Rands, Dec 14 '17 at 18:01
It won't have two keys. complete list follow the above mentioned pattern — Muhammad Haseeb Khan, Dec 14 '17 at 18:06
@MuhammadHaseebKhan In which case why are you using a dict? This entire problem doesn't make sense. — miradulo, Dec 14 '17 at 18:08
@miradulo I wasn't thinking in another way. The chris_rands approach seems easy. But I am just thinking how someone will solve this type of problem. — Muhammad Haseeb Khan, Dec 14 '17 at 18:10
They'll hopefully solve this problem by changing their data structure. — miradulo, Dec 14 '17 at 18:13
@miradulo Yeah, I agree with you but we should have a solution of every type of problem. I think Martin's provided solution can be useful. — Muhammad Haseeb Khan, Dec 14 '17 at 18:15

Martin Evans · Accepted Answer · 2017-12-14T18:04:31.820

2

If your dictionaries always only have a single key then in Python 2.x:

print sorted([{23: (1, 5)}, {59: (2, 3)}, {45: (2, 9)}, {28: (3, 6)}])

Would give:

[{23: (1, 5)}, {28: (3, 6)}, {45: (2, 9)}, {59: (2, 3)}]

By default in Python 2.x using sorted() will result in a correctly sorted list.

For Python 3.x:

print(sorted([{23: (1, 5)}, {59: (2, 3)}, {45: (2, 9)}, {28: (3, 6)}], key=lambda x: next(iter(x))))

This uses a lambda function to extract the first (and only) key from the dictionary and use that as the sorting key.

edited Dec 14 '17 at 18:04

answered Dec 14 '17 at 17:58

Martin Evans

This only works in Python 2, since dict_keys cannot be indexed in Python 3. – miradulo Dec 14 '17 at 18:00
I am using python 3 and can you plz elaborate your answer? – Muhammad Haseeb Khan Dec 14 '17 at 18:01
1

In Python 2, you don't need the key argument at all I think (unless I remember incorrectly how it sorts a list of dicts) – Chris_Rands Dec 14 '17 at 18:02
1

There's no need to create a list, you can use something like: `lambda x: next(iter(x))` – Francisco Dec 14 '17 at 18:04
Thanks for the suggestions, have updated accordingly. – Martin Evans Dec 14 '17 at 18:14

1 Answers1