Sort list of dicts by list index of dictionary

Question

I have a list of dicts, where the dict has a list itself. How can I sort using factors index?

For example sort descending the list by factors[0]

[{'score': '2.0', 'id': 686, 'factors': [2.0, 2.25, 2.75, 1.5, 2.25]}, {'score': '1.9', 'id': 863, 'factors': [1.5, 3.0, 1.5, 2.5, 1.5]}, {'score': '2.0', 'id': 55, 'factors': [1.5, 3.0, 2.5, 1.5, 1.5]}, {'score': '1.9', 'id': 756, 'factors': [1.25, 2.25, 2.5, 2.0, 1.75]}]

Does this answer your question? [How do I sort a list of dictionaries by a value of the dictionary?](https://stackoverflow.com/questions/72899/how-do-i-sort-a-list-of-dictionaries-by-a-value-of-the-dictionary) — Maurice Meyer, Jun 11 '20 at 16:21

score 1 · Answer 1 · answered Jun 11 '20 at 16:23

You can pass it as a key

my_list=[{'score': '2.0', 'id': 686, 'factors': [2.0, 2.25, 2.75, 1.5, 2.25]}, {'score': '1.9', 'id': 863, 'factors': [1.5, 3.0, 1.5, 2.5, 1.5]}, {'score': '2.0', 'id': 55, 'factors': [1.5, 3.0, 2.5, 1.5, 1.5]}, {'score': '1.9', 'id': 756, 'factors': [1.25, 2.25, 2.5, 2.0, 1.75]}]
sorted(my_list, key=lambda x: x['factors'][0])

Output:

[{'score': '1.9', 'id': 756, 'factors': [1.25, 2.25, 2.5, 2.0, 1.75]},
 {'score': '1.9', 'id': 863, 'factors': [1.5, 3.0, 1.5, 2.5, 1.5]},
 {'score': '2.0', 'id': 55, 'factors': [1.5, 3.0, 2.5, 1.5, 1.5]},
 {'score': '2.0', 'id': 686, 'factors': [2.0, 2.25, 2.75, 1.5, 2.25]}]

score 1 · Accepted Answer · answered Jun 11 '20 at 16:26

Essentially what you need to do is use sorted. However this factors[0] seems a bit arbitrary, perhaps you want to sort the list first and then sort by its first value?

However this exmple get the jobs done. Keep in mind it won't be usable for ties, so you might want to add a second sorting key:

sort = sorted(ex, key=lambda x: x['factors'][0])
sort

Output:

[{'factors': [1.25, 2.25, 2.5, 2.0, 1.75], 'id': 756, 'score': '1.9'},
 {'factors': [1.5, 3.0, 1.5, 2.5, 1.5], 'id': 863, 'score': '1.9'}, #Tied values
 {'factors': [1.5, 3.0, 2.5, 1.5, 1.5], 'id': 55, 'score': '2.0'}, #Tied values
 {'factors': [2.0, 2.25, 2.75, 1.5, 2.25], 'id': 686, 'score': '2.0'}]

Example of sorting by factors[0] followed by id for tied values. Please note how the order is the other way around, first you sort by id (inner sort) and then factors in the code (outer sort):

sort = sorted(sorted(ex,key=lambda x: x['id']),key=lambda x: x['factors'][0])
sort

Output:

[{'factors': [1.25, 2.25, 2.5, 2.0, 1.75], 'id': 756, 'score': '1.9'},
 {'factors': [1.5, 3.0, 2.5, 1.5, 1.5], 'id': 55, 'score': '2.0'},
 {'factors': [1.5, 3.0, 1.5, 2.5, 1.5], 'id': 863, 'score': '1.9'},
 {'factors': [2.0, 2.25, 2.75, 1.5, 2.25], 'id': 686, 'score': '2.0'}]

Sort list of dicts by list index of dictionary

2 Answers2