1 itertools.chain(*iterable)

將多個序列作為一個單獨的序列返回

import itertools

for ele in itertools.chain(‘We‘, ‘ are ‘, ‘ champion.‘):
    print ele

output:
W
e
 
a
r
e
 
 
c
h
a
m
p
i
o
n
.

在iter中添加判斷類

2 itertools.compress(data, selector)

返回selector為True的data對應元素

import itertools

for ele in itertools.compress(‘
 
qwer‘, [1,0,1,1]):
    print ele

output:
q
e
r

3 itertools.ifiter(predicate, iterable)

返回predicate結果為True的元素叠代器，如果predicate為None,則返回所有iterable中為True的項

import itertools

for ele in itertools.ifilter(lambda x: x > 5, range(8)):
    print ele

ouput:
6
7

4 itertools.ifterfalse(predicate, iterable)

與itertools.ifiter()正好相反

5 itertools.takewhile(predicate, iterable)

如果predicate為真，則返回iterable元素，如果為假則不再返回，break.

import itertools

for ele in itertools.takewhile(lambda x: x < 5, range(8)):
    print ele

ouput:
0
1
2
3
4

分類

6 itertools.groupby(iterable[,key])

返回一組（key,itera）,key為iterable的值，itera為等於key的所有項

註意：iterable需要先進行sort

import itertools

for key, ele in itertools.groupby([‘abc‘, ‘awe‘, ‘bjf‘, ‘caf‘, ‘bjf‘], key=lambda x: x[0]):
    print key, tuple(ele)

output:
a (‘abc‘, ‘awe‘)
b (‘bjf‘,)
c (‘caf‘,)
b (‘bjf‘,)

list變為iterable

7 itertools.imap(function,*iterables)

相當於叠代器方式的map()

8 itertools.islice(iterable, start,stop[,step])

相當於叠代器方式的切片操作

無限遞增

8 itertools.count(start=0,step=1)

返回以start開始，step遞增的序列，無限遞增

import itertools
for each in itertools.count(start=0, step=2):
    print each

output:
1
2
3
.
.

9 itertools.cycle(iterable)

將叠代器進行無限叠代

import itertools
for each in itertools.cycle(‘ab‘):
    print each

output:
a
b
a
b
.

itertools內置庫