Hold an object, using class in python

Question

I write a program to weave lists of floats together, for example:

l1 = [5.4, 4.5, 8.7]
l2 = [6.5, 7.8]
l3 = [6.7, 6.9]

I want to weave l1 into

Answer 1

Function you wrote returns None, as no return statement is present. Replace print with return and chain calls. You might also need izip_longest instead of zip for lists of nonequal size:

With izip_longest:

from itertools import izip_longest
def weave(l1, l2):
    return filter(None, sum(izip_longest(l1, l2), ())

demo

>>> weave(weave(l1, l2), l3)
(5.4, 6.7, 6.5, 6.9, 4.5, 7.8, 8.7)

Without, zip breaks on shortest argument:

>>> def weave_shortest(l1, l2):
        return sum(zip(l1, l2), ())
>>> weave_shortest(l3, weave_shortest(l1, l2))
(5.4, 6.7, 6.5, 6.9)