Interleave multiple lists of the same length in Python

Question

In Python, is there a good way to interleave two lists of the same length?

Say I\'m given [1,2,3] and [10,20,30]. I\'d like to transform th

Answer 1

For Python>=2.3, there's extended slice syntax:

>>> a = [0, 2, 4, 6, 8]
>>> b = [1, 3, 5, 7, 9]
>>> c = a + b
>>> c[::2] = a
>>> c[1::2] = b
>>> c
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

The line c = a + b is used as a simple way to create a new list of exactly the right length (at this stage, its contents are not important). The next two lines do the actual work of interleaving a and b: the first one assigns the elements of a to all the even-numbered indexes of c; the second one assigns the elements of b to all the odd-numbered indexes of c.