Question

I have two lists of ints, and I want systematically operate their objects. For example I have:

A = [ a1, a2, a3, a4 ...]
B = [ b1, b2, b3 ...]

and I want to print something like this:

a1+b1   a2
a2+b2   a3
a3+b3   a4

I think there are a “for loop” way, but I don’t know how use two variables in a “for loop”.

Answer 1

You could use zip:

>>> A = ['a1', 'a2', 'a3', 'a4']
>>> B = ['b1', 'b2', 'b3']
>>> zip(A[:3], B, A[1:])
[('a1', 'b1', 'a2'), ('a2', 'b2', 'a3'), ('a3', 'b3', 'a4')]
>>> for a, b, c in zip(A[:3], B, A[1:]):
...     print a + '+' + b + '   ' + c
... 
a1+b1   a2
a2+b2   a3
a3+b3   a4