interleave.py

# !/bin/env/python

# or depending how you want to think about it, inverse frequencies. Cahnge these to get different interleaving
A_FREQUENCY = 3
B_FREQUENCY = 5

#two nice friendly looking sequences of the form 'a99','a98','a97'...
#(reverse order so we get the correct order with pop())
a = map( lambda x: 'a'+str(x), range(100,0,-1))
b = map( lambda x: 'b'+str(x), range(100,0,-1))

# do an A_FREQUENCY:B_FREQUENCY pulldown (http://en.wikipedia.org/wiki/Telecine#Other_pulldown_patterns )
for counter in range(1000):
    try:
        if not counter % A_FREQUENCY:
            print a.pop()
        if not counter % B_FREQUENCY:
            print b.pop()
    except IndexError: #one list is empty
        break