Most Pythonic Way to Split an Array by Repeating Elements

Question

I have a list of items that I want to split based on a delimiter. I want all delimiters to be removed and the list to be split when a delimiter occurs twice. F

Answer 1

Too clever by half, and only offered because the obvious right way to do it seems so brute-force and ugly:

class joiner(object):
  def __init__(self, N, data = (), gluing = False):
    self.data = data
    self.N = N
    self.gluing = gluing
  def __add__(self, to_glue):
    # Process an item from itertools.groupby, by either
    # appending the data to the last item, starting a new item,
    # or changing the 'gluing' state according to the number of
    # consecutive delimiters that were found.
    N = self.N
    data = self.data
    item = list(to_glue[1])
    # A chunk of delimiters;
    # return a copy of self with the appropriate gluing state.
    if to_glue[0]: return joiner(N, data, len(item) < N)
    # Otherwise, handle the gluing appropriately, and reset gluing state.
    a, b = (data[:-1], data[-1] if data else []) if self.gluing else (data, [])
    return joiner(N, a + (b + item,))

def split_on_multiple(data, delimiter, N):
  # Split the list into alternating groups of delimiters and non-delimiters,
  # then use the joiner to join non-delimiter groups when the intervening
  # delimiter group is short.
  return sum(itertools.groupby(data, delimiter.__eq__), joiner(N)).data