Python: breaking a list into all possible sublists

Question

Lets assume I've got a list of integers:

mylist = [101, 102, 103, 104, 105, 106]

Now I need to create every possible sublist division (order preserved):

sublists = [([101], [102, 103, 104, 105, 106]),
            ([101, 102], [103, 104, 105, 106]),
            ([101, 102, 103], [104, 105, 106]),
            ...
            ([101, 102], [103, 104], [105, 106]),
            ...
            ([101], [102, 103, 104], [105], [106]),
            ...
            ([101], [102], [103], [104], [105], [106])]

Any idea? Would itertools be helpful?

Answer 1

You are creating slice points; are you slicing after the current element or not. You can generate these with booleans:

from itertools import product

def sublists(lst):
    for doslice in product([True, False], repeat=len(lst) - 1):
        slices = []
        start = 0
        for i, slicehere in enumerate(doslice, 1):
            if slicehere:
                slices.append(lst[start:i])
                start = i
        slices.append(lst[start:])
        yield slices

Demo:

>>> from pprint import pprint
>>> mylist = [101, 102, 103, 104, 105, 106]
>>> pprint(list(sublists(mylist)))
[[[101], [102], [103], [104], [105], [106]],
 [[101], [102], [103], [104], [105, 106]],
 [[101], [102], [103], [104, 105], [106]],
 [[101], [102], [103], [104, 105, 106]],
 [[101], [102], [103, 104], [105], [106]],
 [[101], [102], [103, 104], [105, 106]],
 [[101], [102], [103, 104, 105], [106]],
 [[101], [102], [103, 104, 105, 106]],
 [[101], [102, 103], [104], [105], [106]],
 [[101], [102, 103], [104], [105, 106]],
 [[101], [102, 103], [104, 105], [106]],
 [[101], [102, 103], [104, 105, 106]],
 [[101], [102, 103, 104], [105], [106]],
 [[101], [102, 103, 104], [105, 106]],
 [[101], [102, 103, 104, 105], [106]],
 [[101], [102, 103, 104, 105, 106]],
 [[101, 102], [103], [104], [105], [106]],
 [[101, 102], [103], [104], [105, 106]],
 [[101, 102], [103], [104, 105], [106]],
 [[101, 102], [103], [104, 105, 106]],
 [[101, 102], [103, 104], [105], [106]],
 [[101, 102], [103, 104], [105, 106]],
 [[101, 102], [103, 104, 105], [106]],
 [[101, 102], [103, 104, 105, 106]],
 [[101, 102, 103], [104], [105], [106]],
 [[101, 102, 103], [104], [105, 106]],
 [[101, 102, 103], [104, 105], [106]],
 [[101, 102, 103], [104, 105, 106]],
 [[101, 102, 103, 104], [105], [106]],
 [[101, 102, 103, 104], [105, 106]],
 [[101, 102, 103, 104, 105], [106]],
 [[101, 102, 103, 104, 105, 106]]]

If you want to drop the last entry (containing a list with only one list in it, in turn containing all elements), replace the last 2 lines with:

if start:
    slices.append(lst[start:])
    yield slices