How Can I Delete All Zeros Except For X Of Them In Every Run Of Consecutive Zeros Within A List?

For every run of x or more consecutive zeros in a list in Python, I would like to del all zeros in the run except for x of them. If x = 0, then delete all zeros. I was thinking of

Solution 1:

This is easy to do as a generator. Wrap your call to it in a list constructor if you want a fresh list with the zero-runs removed.

def compact_zero_runs(iterable, max_zeros):
    zeros = 0for i in iterable:
        if i == 0:
            zeros += 1if zeros <= max_zeros:
                yield i
        else:
            zeros = 0yield i

Solution 2:

Using groupby:

defdel_zeros(lst, n):
    lst = (list(j)[:n] if i else list(j) 
           for i,j in itertools.groupby(lst, key=lambdax:x==0))

    return [item for sublist in lst for item in sublist]

And the tests:

>>> [del_zeros(L, i) for i in range(5)][[7, 12, 2, 27, 10, 8],
 [7, 0, 12, 0, 2, 0, 27, 10, 0, 8],
 [7, 0, 12, 0, 0, 2, 0, 0, 27, 10, 0, 0, 8],
 [7, 0, 12, 0, 0, 2, 0, 0, 0, 27, 10, 0, 0, 0, 8],
 [7, 0, 12, 0, 0, 2, 0, 0, 0, 27, 10, 0, 0, 0, 0, 8]]

Solution 3:

from itertools import groupby, chain, islice
from functools import partial
from operator import eq

deff(L, x):
    groups = groupby(L, partial(eq, 0))
    returnlist(chain.from_iterable(islice(v, x) if k else v for k,v in groups))