1 # -*- encoding:utf-8 -*-
 2 import itertools
 3 
 4 
 5 def main():
 6     # chain
 7     print(list(itertools.chain([1,2,3], (3,4,5))))
 8     # count(start=0, step=1)
 9     for item in itertools.count(2, 2):
10         print item
11         if item == 10:
12             break
13     # ifilter(contintion,data)
14     print(list(itertools.ifilter(lambda x : x%2, [1,2,3,4,5,6,7,8,9])))
15     # filterfalse(contintion,data)
16     print(list(itertools.ifilterfalse(None,[1,2,0,1,0,3])))
17     print(list(itertools.ifilterfalse(lambda x : x%2, [1,2,3,4,5,6,7,8,9])))
18     print(list(itertools.ifilterfalse(lambda x : x < 20, (20, 30, 22, 40, 19, 1))))
19     # compress()
20     print(list(itertools.compress([1,0,1], ["a","b","c"])))
21     # starmap(func, [])
22     print(list(itertools.starmap(max,[[1,2,3],[2,3,4],[3,6,9]])))
23     # repeat(object[, times])
24     print(list(itertools.repeat("repeat", 5)))
25     # dropwhile(func, seq );当函数f执行返回假时, 开始迭代序列
26     print(list(itertools.dropwhile(lambda x: x<3, [1,2,3,4,5,6])))
27     # takewhile(func, seq );当函数f执行返回假时, 停止迭代序列
28     print(list(itertools.takewhile(lambda x: x>4, [1,2,3,4,5,6])))
29     # islice(seq[, start], stop[, step]);
30     print(list(itertools.islice(itertools.count(10), 5)))
31     print(list(itertools.islice("1234567890", 1, 8, 2)))
32     # cycle(seq, times)
33     print(list(itertools.islice(itertools.cycle("abc"), 8)))
34     # 建一个迭代器，生成项imap(fn, [], [])
35     print(list(itertools.imap(lambda x,y:"imap: "+str(x)+"+"+str(y), [2,2,2], [3,3,3,4])))
36     # product(iter1,iter2, ... iterN, [repeat=1])
37     # 创建一个迭代器，生成表示item1，item2等中的项目的笛卡尔积的元组，repeat是一个关键字参数，指定重复生成序列的次数
38     for i in itertools.product([1,2,3], [4,5,6], [7,8,9], repeat=1):
39         print i
40     for i in itertools.product([1,2,3], [4,5,6], repeat=2):
41     # for i in itertools.product([1,2,3], [4,5,6], [1,2,3], [4,5,6], repeat=1):
42         print i
43     # permutations(p[,r]);返回p中任意取r个元素做排列的元组的迭代器
44     for i in itertools.permutations([1, 2, 3], 3):
45         print i
46     # combinations(iterable,r);创建一个迭代器，返回iterable中所有长度为r的子序列, note:不带重复
47     print(list(itertools.combinations([1,2,3], 2)))
48     # combinations_with_replacement() 带重复
49     print(list(itertools.combinations_with_replacement([1,2,3], 2)))
50     # tee(iterable [, n])-> (<itertools.tee object at 0x0288CAA8>, <itertools.tee object at 0x0288CAD0>, ...)
51     t1 = itertools.tee([1,2,3], 2)[1]
52     for i in t1:
53         print i
54 
55 
56 if __name__ == '__main__':
57     main()