[英]List comprehension from itertools.cycle generator
My problem was that I needed to deliver batches from an itertools.cycle
generator in list form. 我的问题是我需要以清单形式从itertools.cycle
生成器交付批次。
A cycle
takes an iterable and loops it around itself indefinitely. 一个cycle
需要一个可迭代的循环,并无限期地围绕自身循环。 For example: 例如:
>>> my_cycle = itertools.cycle('abc')
>>> next(my_cycle)
'a'
>>> next(my_cycle)
'b'
>>> next(my_cycle)
'c'
>>> next(my_cycle)
'a'
And so on. 等等。
The question becomes, how do we deliver a list of batch length n
from a cyclic generator, while preserving where we are in the cycle? 问题就变成了,我们如何在保持我们在循环中的位置的同时,从循环发生器中获得批次长度n
的列表?
Desired output is: 所需的输出是:
c = itertools.cycle('abc')
batch_size = 2
Out[0]: ['a', 'b']
Out[1]: ['c', 'a']
Out[2]: ['b', 'c']
I am posting my solution in case someone runs into the same problem. 如果有人遇到相同的问题,我会发布我的解决方案。
>>> size_of_batch = 5
>>> c = itertools.cycle('abcdefg')
>>> [next(c) for _ in range(size_of_batch)]
['a', 'b', 'c', 'd', 'e']
>>> [next(c) for _ in range(size_of_batch)]
['f', 'g', 'a', 'b', 'c']
There is an itertools recipe designed for this: 有一个为此设计的itertools配方 :
from itertools import islice, cycle
def take(n, iterable):
"Return first n items of the iterable as a list"
return list(islice(iterable, n))
c = cycle("abcdefg")
take(5, c)
# ['a', 'b', 'c', 'd', 'e']
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