How to divide python list into sublists of unequal length?

Question

I am trying to divide a list of elements which are comma separated into chunks of unequal length. How can I divide it?

list1 = [1, 2, 1]
list2 = [\"1.1.1.1\", \"         


        

Answer 1

You can use itertools.islice for this too. It's efficient and easy to read:

def unequal_divide(iterable, chunks):
    it = iter(iterable)
    return [list(islice(it, c)) for c in chunks]

Then to use it:

>>> list1 = [1, 2, 1]
>>> list2 = ["1.1.1.1", "1.1.1.2", "1.1.1.3", "1.1.1.4"]
>>> unequal_divide(list1, list2)
[['1.1.1.1'], ['1.1.1.2', '1.1.1.3'], ['1.1.1.4']]

Or as a generator:

def unequal_divide(iterable, chunks):
    it = iter(iterable)
    for c in chunks:
        yield list(islice(it, c))

In use:

>>> list(unequal_divide(list1, list2))
[['1.1.1.1'], ['1.1.1.2', '1.1.1.3'], ['1.1.1.4']]

This is also implemented in more-itertools.split_at. See here for their source code which is almost identical minus allowing no chunks to be provided which is weird.