我有一个Python脚本，它把一个整数列表作为输入，我需要一次处理四个整数。不幸的是，我无法控制输入，否则我将它作为一个四元素元组列表传入。目前，我以这种方式迭代它:
for i in range(0, len(ints), 4):
# dummy op for example code
foo += ints[i] * ints[i + 1] + ints[i + 2] * ints[i + 3]
不过，它看起来很像“C-think”，这让我怀疑有一种更python的方式来处理这种情况。该列表在迭代后被丢弃，因此不需要保留。也许这样会更好?
while ints:
foo += ints[0] * ints[1] + ints[2] * ints[3]
ints[0:4] = []
不过，感觉还是不太对。: - /
相关问题:在Python中如何将列表分割成大小均匀的块?
当前回答
一行程序，特别的解决方案，以4 -大小的块迭代列表x
for a, b, c, d in zip(x[0::4], x[1::4], x[2::4], x[3::4]):
... do something with a, b, c and d ...
其他回答
似乎没有一个漂亮的方法来做到这一点。下面是一个有很多方法的页面，包括:
def split_seq(seq, size):
newseq = []
splitsize = 1.0/size*len(seq)
for i in range(size):
newseq.append(seq[int(round(i*splitsize)):int(round((i+1)*splitsize))])
return newseq
more-itertools包有一个分块方法，它可以做到这一点:
import more_itertools
for s in more_itertools.chunked(range(9), 4):
print(s)
打印
[0, 1, 2, 3]
[4, 5, 6, 7]
[8]
Chunked返回列表中的项。如果你更喜欢迭代对象，可以使用ichunked。
import itertools
def chunks(iterable,size):
it = iter(iterable)
chunk = tuple(itertools.islice(it,size))
while chunk:
yield chunk
chunk = tuple(itertools.islice(it,size))
# though this will throw ValueError if the length of ints
# isn't a multiple of four:
for x1,x2,x3,x4 in chunks(ints,4):
foo += x1 + x2 + x3 + x4
for chunk in chunks(ints,4):
foo += sum(chunk)
另一种方法:
import itertools
def chunks2(iterable,size,filler=None):
it = itertools.chain(iterable,itertools.repeat(filler,size-1))
chunk = tuple(itertools.islice(it,size))
while len(chunk) == size:
yield chunk
chunk = tuple(itertools.islice(it,size))
# x2, x3 and x4 could get the value 0 if the length is not
# a multiple of 4.
for x1,x2,x3,x4 in chunks2(ints,4,0):
foo += x1 + x2 + x3 + x4
修改自Python的itertools文档中的Recipes部分:
from itertools import zip_longest
def grouper(iterable, n, fillvalue=None):
args = [iter(iterable)] * n
return zip_longest(*args, fillvalue=fillvalue)
例子
grouper('ABCDEFG', 3, 'x') # --> 'ABC' 'DEF' 'Gxx'
注意:在Python 2上使用izip_longest而不是zip_longest。
def chunker(seq, size):
return (seq[pos:pos + size] for pos in range(0, len(seq), size))
适用于任何序列:
text = "I am a very, very helpful text"
for group in chunker(text, 7):
print(repr(group),)
# 'I am a ' 'very, v' 'ery hel' 'pful te' 'xt'
print('|'.join(chunker(text, 10)))
# I am a ver|y, very he|lpful text
animals = ['cat', 'dog', 'rabbit', 'duck', 'bird', 'cow', 'gnu', 'fish']
for group in chunker(animals, 3):
print(group)
# ['cat', 'dog', 'rabbit']
# ['duck', 'bird', 'cow']
# ['gnu', 'fish']
