[Tutor] Iterating over two sequences in "parallel"

[Jose Amoreira]

Hi!
I want to process corresponding elements of two lists, sequentially. Call the 
lists list1 and list2, and assume they have equal lengths. I can do something 
like

for index in range(len(list1)):
    process(list1[index], list2[index])

But I find it somehow rather ugly, because we generate yet another an list for 
the index, when we already have the two we want to process. I know we can use 
xrange, but still I find it awkward...

Instead of the above snippet, I am considering something like

while list1:
    process(list1.pop(), list2.pop())

But this has the side effect of emptying both lists, which may not be 
convenient. Of course we can make backup copies of the lists if needed, but we 
are then recovering the previous method ugliness...

Do you guys have any suggestions regarding this? Thanks
Jose Amoreira