python - split list comprehension into nested lists based on a rule -

i have simple list splitting question:

given nested list this:

x = [[1,4,3],[2,3,5,1,3,52,3,5,2,1],[2]] 

i want further split element(sub-list) longer 3, , length multiple of 3 or 3n+1 sub-lists of length 3, except last chunk, result want is:

x2 = [[1,4,3], [2,3,5],[1,3,52],[3,5,2,1],[2]] 

i think can done itertools.groupby and/or yield functions... couldn't put details >> a_function(x)...

 splits = [ a_function(x) if len(x)>3 , (len(x) % 3 == 0 or len(x) % 3 == 1) else x x in x] 

could kindly give me pointers? much.

sometimes, when requirements list comprehension unusual or complicated, use generator function, so:

def gen(l):    sublist in l:        if len(sublist)%3 == 0:            in range(0, len(sublist), 3):                yield sublist[i:i+3]        elif len(sublist)%3 == 1:            in range(0, len(sublist)-4, 3):                yield sublist[i:i+3]            yield sublist[-4:]        else:            yield sublist  # op's data: x = [[1,4,3],[2,3,5,1,3,52,3,5,2],[2]] y = [[1,4,3],[2,3,5,1,3,52,3,5,2,1],[2]]  # using either list comprehension or list constructor: newx = [item item in gen(x)] newy = list(gen(y))  # result: assert newx == [[1, 4, 3], [2, 3, 5], [1, 3, 52], [3, 5, 2], [2]] assert newy == [[1, 4, 3], [2, 3, 5], [1, 3, 52], [3, 5, 2, 1], [2]]