具有记忆的迭代器? [英] Iterator with memory?
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问题描述
我正在开发一个使用马尔可夫链的应用程序。
I'm working on an application which use a markov chain.
此代码的示例如下:
chain = MarkovChain(order=1)
train_seq = ["","hello","this","is","a","beautiful","world"]
for i, word in enum(train_seq):
chain.train(previous_state=train_seq[i-1],next_state=word)
我正在寻找的是迭代train_seq,但保留N个最后元素。
What I am looking for is to iterate over train_seq, but to keep the N last elements.
for states in unknown(train_seq,order=1):
# states should be a list of states, with states[-1] the newest word,
# and states[:-1] should be the previous occurrences of the iteration.
chain.train(*states)
希望我的问题描述足够明确
Hope the description of my problem is clear enough for
推荐答案
窗口
会给你 n
一次来自 iterable
的商品。
window
will give you n
items from iterable
at a time.
from collections import deque
def window(iterable, n=3):
it = iter(iterable)
d = deque(maxlen = n)
for elem in it:
d.append(elem)
yield tuple(d)
print [x for x in window([1, 2, 3, 4, 5])]
# [(1,), (1, 2), (1, 2, 3), (2, 3, 4), (3, 4, 5)]
如果您想要前几次相同数量的商品,
If you want the same number of items even the first few times,
from collections import deque
from itertools import islice
def window(iterable, n=3):
it = iter(iterable)
d = deque((next(it) for Null in range(n-1)), n)
for elem in it:
d.append(elem)
yield tuple(d)
print [x for x in window([1, 2, 3, 4, 5])]
会这样做。
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