การใช้ itertools.groupby ใน Python

data = [
  (10, "ten"),
  (1, "one"),
  (2, "two"),
  (5, "five"),
  (20, "twenty"),
  (3, "three"),
  (1, "one-one"),
  (7, "seven"),
  (2, "two-two"),
  (3, "three-three"),
  (1, "one-one-one"),
  (5, "five-five"),
]

{1: ['one', 'one-one', 'one-one-one']}
{2: ['two', 'two-two']}
{3: ['three', 'three-three']}
{5: ['five', 'five-five']}
{7: ['seven']}
{10: ['ten']}
{20: ['twenty']}

from itertools import groupby
from operator import itemgetter
for k, g in groupby(data, key=itemgetter(0)):
  {k: list(map(itemgetter(1), g))}

{10: ['ten']}
{1: ['one']}
{2: ['two']}
{5: ['five']}
{20: ['twenty']}
{3: ['three']}
{1: ['one-one']}
{7: ['seven']}
{2: ['two-two']}
{3: ['three-three']}
{1: ['one-one-one']}
{5: ['five-five']}

for k, g in groupby(sorted(data), key=itemgetter(0)):
  {k: list(map(itemgetter(1), g))}

{1: ['one', 'one-one', 'one-one-one']}
{2: ['two', 'two-two']}
{3: ['three', 'three-three']}
{5: ['five', 'five-five']}
{7: ['seven']}
{10: ['ten']}
{20: ['twenty']}