a = [1,2,2,3,3,4,5,6]

1、第一種方法def get_unique_N(iterable, N):

"""Yields (in order) the first N unique elements of iterable.

Might yield less if data too short."""

seen = set()

for e in iterable:

if e in seen:

continue

seen.add(e)

yield e

if len(seen) == N:

return

k = get_unique_N([1,2,2,3,3,4,5,6], 4)

print(list(k))

輸出結(jié)果：

[1,2,3,4]

2、第二種方法def unique_everseen_limit(iterable, limit=5):

seen = set()

seen_add = seen.add

for element in iterable:

if element not in seen:

seen_add(element)

yield element

if len(seen) == limit:

break

res = list(unique_everseen_limit(a)) # [1, 2, 3, 4, 5]

3、第三種方法from itertools import islice

def unique_everseen(iterable):

seen = set()

seen_add = seen.add

for element in iterable:

if element not in seen:

seen_add(element)

yield element

res = list(islice(unique_everseen(a), 5)) # [1, 2, 3, 4, 5]

4、第四種方法from itertools import islice

from more_itertools import unique_everseen

from toolz import unique

res = list(islice(unique_everseen(a), 5)) # [1, 2, 3, 4, 5]

res = list(islice(unique(a), 5)) # [1, 2, 3, 4, 5]

總結(jié)

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