使用unique_everseen
配方和collections.Counters
:
from collections import Counter
def solve(lst):
counters = map(Counter, lst)
return [ [uniq]*c[uniq] for seq, c in zip(lst, counters)
for uniq in unique_everseen(seq)]
演示:
>>> print(solve([[1, 2, 2, 1], [3, 4, 3]]))
[[1, 1], [2, 2], [3, 3], [4]]
>>> print(solve([['hello', 'hello', 'hello', 'what'], ['i', 'am', 'i']]))
[['hello', 'hello', 'hello'], ['what'], ['i', 'i'], ['am']]
>>> print(solve([[1,2,3,2,1],[9,8,7,8,9],[5,4,6,4,5]]))
[[1, 1], [2, 2], [3], [9, 9], [8, 8], [7], [5, 5], [4, 4], [6]]
如您所见,这也保留了项目的顺序。
unique_everseen
配方代码:
from itertools import filterfalse
def unique_everseen(iterable, key=None):
"List unique elements, preserving order. Remember all elements ever seen."
# unique_everseen('AAAABBBCCDAABBB') --> A B C D
# unique_everseen('ABBCcAD', str.lower) --> A B C D
seen = set()
seen_add = seen.add
if key is None:
for element in filterfalse(seen.__contains__, iterable):
seen_add(element)
yield element
else:
for element in iterable:
k = key(element)
if k not in seen:
seen_add(k)
yield element