python列表字典嵌套时，如何对字典value值相同的进行分组？

Question

a = [{"name": 'tom', "age": '18'}, {"name": "jack", "age": "42"}, {"key": "lily", "age": "18"}]

如何把age相同的字典分组取出来呢？？

Answer 1

from itertools import groupby
from operator import itemgetter

rows = [{"name": 'tom', "age": 1}, {"name": "jack", "age": 12}, {"name": "lily", "age": 12}]

for date, items in groupby(rows, key=itemgetter('')):
    print (date,list(items))

Answer 2

import pandas as pd

a = [
{"name": 'tom', "age": '18'}, 
{"name": "jack", "age": "42"}, 
{"name": "lily", "age": "18"}]

df = pd.DataFrame(a)

res = [{"age":k, "name":g["name"].tolist()} for k, g in df.groupby("age")]

print(res)

[{'age': '18', 'name': ['tom', 'lily']}, {'age': '42', 'name': ['jack']}]