Python: split a list based on a condition?

Question

What\'s the best way, both aesthetically and from a performance perspective, to split a list of items into multiple lists based on a conditional? The equivalent of:

Answer 1

For example, splitting list by even and odd

arr = range(20)
even, odd = reduce(lambda res, next: res[next % 2].append(next) or res, arr, ([], []))

Or in general:

def split(predicate, iterable):
    return reduce(lambda res, e: res[predicate(e)].append(e) or res, iterable, ([], []))

Advantages:

• Shortest posible way
• Predicate applies only once for each element

Disadvantages

• Requires knowledge of functional programing paradigm