Question

my language is python

the input looks something like:

'0 0 0 0 1 0 0 0 1 1 0 0' 

and so on.

i want the output:

('0 0 0 0', '1 0 0 0', '1 1 0 0') 

or every set of 4 numbers in is its own element

so far i have put together

>>> truth = re.compile('(([0-1]\D*?){4})*')
>>> truth.search('0 0 0 0 1 0 0 0').groups()
('0 0 0 0', '0')

or and several similar things but nothing is getting closer. a few things here are new to me and i’m reading the docs but can’t seem to piece together whats falling apart. Notable i don’t now why i get that last 0…

the input will eventually be many many lines but if it works for small case i’m sure it will translate over.

thanks

Answer 1

I wouldn’t use a regular expression for this. Instead use grouper from the recipes on the itertools documentation:

>>> [' '.join(x) for x in grouper(4, truth.split())]

See it working online: ideone

---

Here’s the source code for grouper (copied from the itertools documentation):

from itertools import izip_longest

def grouper(n, iterable, fillvalue=None):
    "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
    args = [iter(iterable)] * n
    return izip_longest(fillvalue=fillvalue, *args)