A python problem from v2ex: https://www.v2ex.com/t/308543#;

v2ex_308543.py

# -*- coding: utf-8 -*-
t1 = [{'id':1, 'abc':'2'}, {'id':1, 'abc':'3'}, {'id':2, 'abc':'2'}]
t2 = []
ids = []

# Get all id values
for item in t1:
    ids.append(item['id'])

ids = sorted(list(set(ids)))

# For each id get according 'abc' values and generate the result
for i in ids:
    temp = []
    for item in t1:
        if item['id'] == i:
            temp.append(item['abc'])
    if len(temp) == 1:
        temp = temp[0]
    else:
        temp.sort()
    t2.append({'id':i, 'abc':temp})

print(t2)