标签：链接 lambda split c函数 red tar filter click 选择
文档 链接
pymotw 链接
生成一个无限迭代的数字队列, 只有进行
其实数字以及步幅
start, [step]
start, start+step, start+2*step, ...
count(10) --> 10 11 12 13 14 ...
from itertools import * import time c = count(10,5) print c for i in c: time.sleep(0.5) print i """ count(10, 5) 10 15 20 25 30 35 40 45 50 55 Process finished with exit code -1 """
传入一个可迭代对象然后循环遍历此对象
p
p0, p1, ... plast, p0, p1, ...
cycle(‘ABCD‘) --> A B C D A B C D ...
from itertools import * import time c = cycle([1, 2, 3]) print c for i in c: time.sleep(0.5) print i """ <itertools.cycle object at 0x0000000002A42088> 1 2 3 1 2 3 1 2 Process finished with exit code -1 """
传入一个对象, 以及数字, 遍历此对象指定数字次数
elem [,n]
elem, elem, elem, ... endlessly or up to n times
repeat(10, 3) --> 10 10 10
from itertools import * import time c = repeat(3, 5) print c for i in c: time.sleep(0.5) print i """ repeat(3, 5) 3 3 3 3 3 Process finished with exit code 0 """
传入多个序列, 遍历时将多个序列串联一起进行
p, q, ...
p0, p1, ... plast, q0, q1, ...
chain(‘ABC‘, ‘DEF‘) --> A B C D E F
from itertools import * c = chain(range(5), range(3)) print c for i in c: print i """ <itertools.chain object at 0x0000000002A77FD0> 0 1 2 3 4 0 1 2 Process finished with exit code 0r """
参数传入一个序列以及一个选择列表，对数据序列基于选择列表进行筛选
data, selectors
(d[0] if s[0]), (d[1] if s[1]), ...
compress(‘ABCDEF‘, [1,0,1,0,1,1]) --> A C E F
from itertools import * c = compress("hahahahahaha", [1, 0, 1, 0, 1, 0, 1, 0]) print c for i in c: print i """ <itertools.compress object at 0x0000000002B01048> h h h h Process finished with exit code 0 """
创建一个迭代器，只要函数predicate(item)为True，就丢弃iterable中的项，如果predicate返回False，就会生成iterable中的项和所有后续项。
即：在条件为false之后的第一次, 返回迭代器中剩下来的项.
pred, seq
seq[n], seq[n+1], starting when pred fails
dropwhile(lambda x: x<5, [1,4,6,4,1]) --> 6 4 1
def dropwhile(predicate, iterable): # dropwhile(lambda x: x<5, [1,4,6,4,1]) --> 6 4 1 iterable = iter(iterable) for x in iterable: if not predicate(x): yield x break for x in iterable: yield x
from itertools import * def should_drop(x): print ‘Testing:‘, x return (x<1) for i in dropwhile(should_drop, [ -1, 0, 1, 2, 3, 4, 1, -2 ]): print ‘Yielding:‘, i Testing: -1 Testing: 0 Testing: 1 Yielding: 1 Yielding: 2 Yielding: 3 Yielding: 4 Yielding: 1 Yielding: -2
按照keyfunc函数对序列每个元素执行后的结果分组(每个分组是一个迭代器), 返回这些分组的迭代器
iterable[, keyfunc]
sub-iterators grouped by value of keyfunc(v)
chain(‘ABC‘, ‘DEF‘) --> A B C D E F
迭代器 参数 结果 例子 ifilter() pred, seq elements of seq where pred(elem) is True ifilter(lambda x: x%2, range(10)) --> 1 3 5 7 9 ifilterfalse() pred, seq elements of seq where pred(elem) is False ifilterfalse(lambda x: x%2, range(10)) --> 0 2 4 6 8 islice() seq, [start,] stop [, step] elements from seq[start:stop:step] islice(‘ABCDEFG‘, 2, None) --> C D E F G imap() func, p, q, ... func(p0, q0), func(p1, q1), ... imap(pow, (2,3,10), (5,2,3)) --> 32 9 1000 starmap() func, seq func(*seq[0]), func(*seq[1]), ... starmap(pow, [(2,5), (3,2), (10,3)]) --> 32 9 1000 tee() it, n it1, it2 , ... itn splits one iterator into n takewhile() pred, seq seq[0], seq[1], until pred fails takewhile(lambda x: x<5, [1,4,6,4,1]) --> 1 4 izip() p, q, ... (p[0], q[0]), (p[1], q[1]), ... izip(‘ABCD‘, ‘xy‘) --> Ax By izip_longest() p, q, ... (p[0], q[0]), (p[1], q[1]), ... izip_longest(‘ABCD‘, ‘xy‘, fillvalue=‘-‘) --> Ax By C- D-
标签：链接 lambda split c函数 red tar filter click 选择
原文地址：https://www.cnblogs.com/shijieli/p/11025224.html
