List of dicts, group without intersection by list keys

user_14758190 0
Viewed 145

I need help to optimize my code.

I have a data:

data = [
  {"ids": [1]},
  {"ids": [3, 4]},
  {"ids": [1, 2]},
  {"ids": [2]},
]

and I need to group it without intersection by ids, so expected data should be:

expected = [
  [{"ids": [1]}, {"ids": [2]}],
  [{"ids": [3, 4]}, {"ids": [1, 2]}],
]  # only 2 sublist here

My code to split(not optimized):

import itertools as it

def _split(
    list_of_dicts,
):
    splitted_list_of_dicts = []
    sub_list = []
    while list_of_dicts:
        for dct in list_of_dicts:
            ids_in_sub_list = set(
                it.chain(*[sub_list_el["ids"] for sub_list_el in sub_list]),
            )
            if not set(dct["ids"]).intersection(ids_in_sub_list):
                sub_list.append(dct)
                list_of_dicts.remove(dct)
        splitted_list_of_dicts.append(sub_list)
        sub_list = []
    return splitted_list_of_dicts

The result of my code is:

result = [
    [{'ids': [1]}, {'ids': [2]}],
    [{'ids': [3, 4]}],
    [{'ids': [1, 2]}]
]  # 3 sublist

I get one more list, which I try to optimize. If you have any ideas on how to help me, I'll be happy, thanks for your time.

More examples:

data = [
  {"ids": [1]},
  {"ids": [3, 4]},
  {"ids": [1, 2]},
  {"ids": [4]},
  {"ids": [3]},
  {"ids": [2]},
]

can be grouped as 2 elements list:

expected = [
    [{'ids': [1]}, {'ids': [4]}, {'ids': [2]}, {'ids': [3]}],
    [{'ids': [3, 4]}, {'ids': [1, 2]}],
]

but now I got all 4:

result = [
    [{'ids': [1]}, {'ids': [4]}, {'ids': [2]}],
    [{'ids': [3, 4]}],
    [{'ids': [1, 2]}],
    [{'ids': [3]}]
]
itertools list dictionary python
2 Answers

If any combination that doesn't contain duplicates is acceptable, you could simply iterate over the data list and append the current element to the first element in the result where none of the ids already exist.

def split(list_of_dicts):
    result_helper = [set()] # This will be a list of sets for easy membership checks
    result_list = [[]] # This will be what we return
    for d in list_of_dicts:
        for s, l, in zip(result_helper, result_list):
            if not any(x in s for x in d["ids"]):
                s.update(d["ids"])
                l.append(d)
                break
        else:
            # for loop ended without being broken
            # This means no elements of result_list took this dict item. 
            # So create a new element
            result_list.append([d])
            result_helper.append(set(d["ids"]))
    return result_list

With your original data,

data = [
  {"ids": [1]},
  {"ids": [3, 4]},
  {"ids": [1, 2]},
  {"ids": [2]},
]
split(data)

we get the output:

 [
    [{'ids': [1]}, {'ids': [3, 4]}, {'ids': [2]}],
    [{'ids': [1, 2]}]
 ]

which seems to be an acceptable solution because none of the lists have a duplicated id.

And with the second example:

data = [
  {"ids": [1]},
  {"ids": [3, 4]},
  {"ids": [1, 2]},
  {"ids": [4]},
  {"ids": [3]},
  {"ids": [2]},
]
split(data)

This gives the output:

 [
    [{'ids': [1]}, {'ids': [3, 4]}, {'ids': [2]}],
    [{'ids': [1, 2]}, {'ids': [4]}, {'ids': [3]}]
 ]

No duplicates in this case either.

user_8439530

As far as I can tell from your question, you are essentially sorting the ids on each group's cardinality.

from itertools import groupby


def transform(data):
    cardinality = lambda x: len(x['ids'])
    sorted_data = sorted(data, key=cardinality)
    return [list(group) for _, group in groupby(sorted_data, key=cardinality)]

Giving:

[
    [
        {'ids': [1]},
        {'ids': [4]},
        {'ids': [3]},
        {'ids': [2]}
    ],
    [
        {'ids': [3, 4]},
        {'ids': [1, 2]}
    ]
]
user_60910170
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