Sort Dict by Values in Python 3.6+

Question

I was looking for a method to sort a dictionary in Python with its values, after a few attempts, is what it comes:

a = {<populated dict...>}
a = {v: k for k, v in a.items()}
a = {v: k for k, v in sorted(a.items())}

This code seems to work, but I think it's poor for performance, is there a better way?

Possible duplicate of [How can I sort a dictionary by key?](https://stackoverflow.com/questions/9001509/how-can-i-sort-a-dictionary-by-key) — abc, Sep 02 '18 at 23:54
@newbie, not sure how a question that sorts by key is a dupe for one asking for sort by value? — Stephen Rauch, Sep 02 '18 at 23:56

score 18 · Answer 1 · edited Jun 20 '20 at 09:12

18

You do not need to do the double key/value swap, you can do this:

a = {k: v for k, v in sorted(a.items(), key=lambda x: x[1])}

(sorted DOCS)

Test Code:

data = dict(a=1, b=3, c=2)
print(data)
data_sorted = {k: v for k, v in sorted(data.items(), key=lambda x: x[1])}
print(data_sorted)

Results:

From CPython 3.6:

{'a': 1, 'b': 3, 'c': 2}
{'a': 1, 'c': 2, 'b': 3}

edited Jun 20 '20 at 09:12

Community

1
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answered Sep 02 '18 at 23:49

Stephen Rauch

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In what way will this sort the dictionary? – Peter Wood Sep 02 '18 at 23:58
@PeterWood, In CPython 3.6 and Python 3.7+ Dicts are ordered. – Stephen Rauch Sep 02 '18 at 23:59
1

I don't like it as an approach. Insertion sort is a feature since 3.6 but `The order-preserving aspect of this new implementation is considered an implementation detail and should not be relied upon` from the [documentation](https://docs.python.org/3/whatsnew/3.6.html) – abc Sep 03 '18 at 00:09
3

@newbie, your are technically correct. However, for 99% of the world, CPython is Python. And for this feature at least, in 3.7 it is no longer an implementation detail. – Stephen Rauch Sep 03 '18 at 00:10

score 3 · Accepted Answer · answered Aug 17 '21 at 04:40

By default, the dictionary is sorted based on keys, but the sorted function takes a function as a parameter using which you can alter the behaviour for program.

d={'a':6,'b':4,'k':3}
print(sorted(d)) 

sorted_by_values= sorted(d,key=lambda x:d[x])
print(sorted_by_values)

score 1 · Answer 3 · answered Nov 23 '19 at 16:13

1

The following code works for me. Not sure how efficient is this.

sorted_list_by_value=sorted(data_dict, key=data_dict.__getitem__)

answered Nov 23 '19 at 16:13

BusBar_යසස්

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score 0 · Answer 4 · answered Sep 03 '18 at 03:01

0

from collections import OrderedDict

otherwise create a list of keys in the order you want.

answered Sep 03 '18 at 03:01

Schalton

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Sort Dict by Values in Python 3.6+

4 Answers4

Test Code:

Results:

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