作者:Shawn
python3.7
文档:
https://docs.python.org/3/library/itertools.html
重写基于https://blog.csdn.net/weixin_41084236/article/details/81179704
itertools.count(start=0,step=1)
>>> for i in itertools.count():
print(i)
0
1
2
3
4
...
itertools.cycle(iterable)
>>> for i in itertools.cycle([2,3,4,5]):
print(i)
2
3
4
5
2
3
4
5
2
...
itertools.repeat(object[,times])
>>> for i in itertools.repeat('雪碧'):
print(i)
雪碧
雪碧
雪碧
雪碧
雪碧
...
itertools.accumulate(iterable[, func])
>>> for i in itertools.accumulate([1,2,3,4],operator.add):
print(i)
1
3
6
10
>>> for i in itertools.accumulate([1,2,3,4],operator.mul):
print(i)
1
2
6
24
itertools.chain(*iterables)
>>> a='把你的心'
>>> b=' 我的心'
>>> c=' 串一串'
>>> for i in itertools.chain(a,b,c):
print(i)
把
你
的
心
我
的
心
串
一
串
chain.from_iterable(iterable)
>>> d=['串一株幸运草',' 串一个同心圆']
>>> for i in itertools.chain.from_iterable(d):
print(i)
串
一
株
幸
运
草
串
一
个
同
心
圆
itertools.compress(data,selectors)
>>> selec=[True,False,42,0,-42,'shuang']
>>> items=['mole','xiangxiangji','tazhenmei','wodene','migang','shuangsile']
>>> for i in itertools.compress(items,selec):
print(i)
mole
tazhenmei
migang
shuangsile
itertools.dropwhile(predicate, iterable)
>>> for i in itertools.dropwhile(lambda x:x<7,[1,2,3,6,7,8,2,4,5,9]):
print(i)
7
8
2
4
5
9
itertools.filterfalse(predicate, iterable)
>>> for i in itertools.filterfalse(lambda x:x=='moyu',['moyu','jinye']):
print(i)
jinye
itertools.groupby(iterable, key=None)
>>> for k,g in itertools.groupby('aaAAaBBBCCCCC'):
print(k)
print(list(g))
a
['a', 'a']
A
['A', 'A']
a
['a']
B
['B', 'B', 'B']
C
['C', 'C', 'C', 'C', 'C']
itertools.islice(iterable, stop)
itertools.islice(iterable, start, stop[, step])
>>> for i in itertools.islice('fengliutitangShawn',0,None,2):
print(i)
f
n
l
u
i
a
g
h
w
itertools.starmap(function, iterable)
>>> for i in itertools.starmap(operator.add,[(1,2),(3,4),(5,6)]):
print(i)
3
7
11
itertools.takewhile(predicate, iterable)
>>> for i in itertools.takewhile(lambda x:x=='moyu',['moyu','jinye']):
print(i)
moyu
itertools.tee(iterable, n=2)
>>> for i in itertools.tee([1,2,3,4,5,6]):
for j in i:
print(j)
1
2
3
4
5
6
1
2
3
4
5
6
itertools.zip_longest(*iterables[,fillvalue=none])
>>> for i in itertools.zip_longest('Twilight Sparkle','Rainbow Dash','Fluttershy','Apple Bloom',fillvalue='Biu'):
print(i)
('T', 'R', 'F', 'A')
('w', 'a', 'l', 'p')
('i', 'i', 'u', 'p')
('l', 'n', 't', 'l')
('i', 'b', 't', 'e')
('g', 'o', 'e', ' ')
('h', 'w', 'r', 'B')
('t', ' ', 's', 'l')
(' ', 'D', 'h', 'o')
('S', 'a', 'y', 'o')
('p', 's', 'Biu', 'm')
('a', 'h', 'Biu', 'Biu')
('r', 'Biu', 'Biu', 'Biu')
('k', 'Biu', 'Biu', 'Biu')
('l', 'Biu', 'Biu', 'Biu')
('e', 'Biu', 'Biu', 'Biu')
itertools.product(*iterables[,repeat=1])
>>> for i in itertools.product('Tom','Jerry',repeat=1):
print(i)
('T', 'J')
('T', 'e')
('T', 'r')
('T', 'r')
('T', 'y')
('o', 'J')
('o', 'e')
('o', 'r')
('o', 'r')
('o', 'y')
('m', 'J')
('m', 'e')
('m', 'r')
('m', 'r')
('m', 'y')
itertools.permutations(iterable[,r])
import itertools
digi=[1,2,3]
for item in itertools.permutations(digi,2):
print(item)
for item in itertools.permutations(range(3)):
print(item)
(1, 2)
(1, 3)
(2, 1)
(2, 3)
(3, 1)
(3, 2)
(0, 1, 2)
(0, 2, 1)
(1, 0, 2)
(1, 2, 0)
(2, 0, 1)
(2, 1, 0)
itertools.combinations(iterable, r)
itertools.combinations_with_replacement(iterable, r)
import itertools
digi=[1,2,3]
for item in itertools.combinations(digi,2):
print(item)
print ("\n")
for item in itertools.combinations(range(3),2):
print (item)
(1, 2)
(1, 3)
(2, 3)
(0, 1)
(0, 2)
(1, 2)
import itertools
digi=[1,2,3]
for item in itertools.combinations_with_replacement(digi,2):
print(item)
(1, 1)
(1, 2)
(1, 3)
(2, 2)
(2, 3)
(3, 3)