Python - How to sort multidimensional list to two-dimensional list?

Question

How i can sort multidimensional list to two-dimensional list?

Multidimensional input: [8, [6, 7, [-1], [4, [[10]]], 2], 1]

Desired two-dimension

Answer 1

My option with recursion and without any dependencies:

lst = [8, [6, 7, [-1], [4, [[10]]], 2], 1]

def flat_group(lst, deep = 0, res = None):
  if res == None: res = []
  for item in lst:
    if len(res) <= deep: res.append([])
    if not type(item) == list:
      res[deep].append((item))
    else:
      flat_group(item, deep + 1, res)
  return res


print(flat_group(lst))
#=> [[8, 1], [6, 7, 2], [-1, 4], [], [10]]

---

To show How it works, I split the method in two:

def flat(lst, deep = 0, res = []):
  for item in lst:
    if not type(item) == list:
      res.append((deep, item))
    else:
      flat(item, deep + 1, res)
  return res

def group(lst):
  flatten = flat(lst)
  max_n = max(flatten)[0]
  res = [[] for _ in range(0,max_n+1)]
  for deep, item in flatten:
    res[deep].append(item)
  return res

print(group(lst))
#=> [[8, 1], [6, 7, 2], [-1, 4], [], [10]]

flat(lst) is a recursive method that builds a flat list of tuples where each tuple contains the value and the deep inside the original list. So the call flat(lst) returns:

# [(0, 8), (1, 6), (1, 7), (2, -1), (2, 4), (4, 10), (1, 2), (0, 1)]

Then group(lst) builds a list of n+1 empty sub-list, where n is the maximum depth, it iterates over the result of flat(lst) and append each element by index to the proper sub-list.

The flat_group(lst) does almost the same.