Group list of dictionaries to list of list of dictionaries with same property value

Question

I have list of dictionaries and every dictionary has property person_id

[{\'person_id\': 1, \'something..\': \'else\'}, {\'person_id\': 3, \'something..\': \'els         


        

Answer 1

Your input isn't sorted by person_id, so use a collections.defaultdict() approach with a loop:

from collections import defaultdict

grouped = defaultdict(list)

for person in inputlist:
    grouped[person['person_id']].append(person)

grouped = grouped.values()

This sorts the input list into buckets, then places all the buckets back into an outer list. If you need the output to be sorted by id, you could use:

grouped = [grouped['pid'] for pid in sorted(grouped)]

If you need the original list in sorted order, or can produce it in sorted order, you can also use itertools.groupby() to do your grouping:

from itertools import groupby
from operator import itemgetter

grouped = [list(g) for p, g in groupby(inputlist, key=itemgetter('person_id'))]

but this does require that inputlist is sorted first.