How to sort a list of nested dictionaries with different keys

Question

I have the following list:

mylist = [
   { 'frame': { 'aaa': 50 } },
   { 'frame': { 'bbb': 12 } },
   { 'frame': { 'ccc': 23 } },
   { 'frame': { 'ddd': 72 } }
]

I was hoping to sort the list based on those integer values with different keys 'aaa', bbb', 'ccc', etc.

I have seen this question but the keys are consistent to this problem.

Any help is highly appreciated!

EDIT: My desired output is:

sorted_list = [
       { 'frame': { 'ddd': 72 } },
       { 'frame': { 'aaa': 50 } },
       { 'frame': { 'ccc': 23 } },
       { 'frame': { 'bbb': 12 } }
]

Do the dictionaries always have only one key/value pair? If so, sort by the fist item in values(). — Mark
– Mark, Commented Mar 26, 2021 at 0:03
I don't understand. What is the expected result for this input? Which key/value pair will you care about from the nested dictionary, and how do you know? — Karl Knechtel
– Karl Knechtel, Commented Mar 26, 2021 at 0:05
@MarkM yes. In my case, the key is 'frame' and its value is a dictionary. — J. A. De la Peña
– J. A. De la Peña, Commented Mar 26, 2021 at 0:05
Anyway, the approach is the same as in the linked answer. You need to be able to write a function that tells you a value that corresponds to each item of mylist, and then you will sort according to those values, by using key=. — Karl Knechtel
– Karl Knechtel, Commented Mar 26, 2021 at 0:06
"In my case, the key is 'frame' and its value is a dictionary" No; we're talking about that dictionary which is the value. — Karl Knechtel
– Karl Knechtel, Commented Mar 26, 2021 at 0:06

Andrej Kesely · Accepted Answer · 2021-03-26 00:12:20Z

1

mylist = sorted(mylist, key=lambda k: -list(k["frame"].values())[0])
print(mylist)

Prints:

[{'frame': {'ddd': 72}}, 
 {'frame': {'aaa': 50}}, 
 {'frame': {'ccc': 23}}, 
 {'frame': {'bbb': 12}}]

answered Mar 26, 2021 at 0:12

Andrej Kesely

196k15 gold badges60 silver badges105 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Karl Knechtel Over a year ago

Instead of negating the value returned by the lambda, you can also use reverse=True in the sorted call. Like: sorted(mylist, key=lambda k: list(k["frame"].values())[0], reverse=True). This has the advantage that it also works for key functions that compute a non-numeric (but still sortable) result (such as a string).

Open AI - Opting Out · Accepted Answer · 2021-03-26 00:27:01Z

1

You can use sorted with a lambda for the key which just returns the first value stored in the dict under the 'frame' key.

We get the first value by using next with iter. This avoids creating a new list object.

We also pass the reverse parameter as True, so we get biggest numbers first. :

>>> mylist = [
...    { 'frame': { 'aaa': 50 } },
...    { 'frame': { 'bbb': 12 } },
...    { 'frame': { 'ccc': 23 } },
...    { 'frame': { 'ddd': 72 } }
... ]

>>> sorted(mylist, key=lambda d: next(iter(d['frame'].values())), reverse=True)
[{'frame': {'ddd': 72}},
 {'frame': {'aaa': 50}},
 {'frame': {'ccc': 23}},
 {'frame': {'bbb': 12}}]

answered Mar 26, 2021 at 0:27

Open AI - Opting Out

24.3k7 gold badges66 silver badges102 bronze badges

Comments

jbflow · Accepted Answer · 2021-03-26 00:14:44Z

0

A slight tweak to the answer in that question gets you this which works.

sorted_list = sorted(mylist, key=lambda k: k['frame'][list(k['frame'].keys())[0]], reverse=True)

Essentially it just goes down into the list, To then sort by the values. Set reverse to True to get it to reverse the list.

edited Mar 26, 2021 at 0:14

answered Mar 26, 2021 at 0:09

jbflow

6524 silver badges22 bronze badges

Collectives™ on Stack Overflow

How to sort a list of nested dictionaries with different keys

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related