我有一个序列,窗口大小和步骤:
seq = [0,1,2,3,4]
n=4
step=2
from more_itertools import windowed
list(windowed([0,1,2,3,4], n, fillvalue=0, step=step))
结果:
[(0, 1, 2, 3), (2, 3, 4, 0)]
但是我需要:
[(0, 1, 2, 3), (2, 3, 4, 0), (4, 0, 0, 0)]
请帮我找到解决方案
这也应该适用于可迭代对象,而不仅仅是序列:
from itertools import islice
def sliding_window(seq, n, step, fillvalue=None):
it = iter(seq)
values = tuple(islice(it, n))
while values:
yield values + (n-len(values)) * (fillvalue, )
values = values[step:] + tuple(islice(it, step))
函数输出:
print(list(sliding_window(seq, n, step, fillvalue=0)))
# [(0, 1, 2, 3), (2, 3, 4, 0), (4, 0, 0, 0)]
其中大部分是从原始 itertools 的滑动窗口配方中借来的。
只需编写自己的windowed
函数:
def windowed(iterable, size, fillvalue=None, step=1):
for i in range(0, len(iterable), step):
window = iterable[i:i+size]
window += [fillvalue] * (size - len(window))
yield window
>>> list(windowed([0,1,2,3,4], 4, fillvalue=0, step=2))
[[0, 1, 2, 3], [2, 3, 4, 0], [4, 0, 0, 0]]
使用padded怎么样?
seq = [0,1,2,3,4]
n=4
step=2
from more_itertools import windowed, padded
list(windowed(padded(seq, 0, n=n, next_multiple=True), n, step=step))
给定
import itertools as it
import more_itertools as mit
iterable = [0, 1, 2, 3, 5]
代码
从滑动窗口获取所有结果:
windows = list(mit.stagger(iterable, offsets=(0, 1, 2, 3), longest=True, fillvalue=0))
windows
# [(0, 1, 2, 3), (1, 2, 3, 5), (2, 3, 5, 0), (3, 5, 0, 0), (5, 0, 0, 0)]
接下来,过滤掉想要的结果:
[w for i, w in enumerate(windows) if not (i % 2)]
# [(0, 1, 2, 3), (2, 3, 5, 0), (5, 0, 0, 0)]
或切片可迭代:
list(it.islice(windows, 0, None, 2))
# [(0, 1, 2, 3), (2, 3, 5, 0), (5, 0, 0, 0)]