[Tutor] Iterate over multiple objects

A.T.Hofkamp a.t.hofkamp at tue.nl
Wed Oct 29 12:38:31 CET 2008

W W wrote:
> Hi,
> I'm trying to compare two strings because I want to find the difference.
> i.e.
> string1 = "foobar"
> string2 = "foobzr"
> is there a simple way to do this with a for loop? This is the method I
> tried, but it gives me an error:
> In [14]: for x, y in bar[0], bar[1]:
>    ....:     print x, y

With the zip() function you can merge two sequences into one:

for x, y in zip(string1, string2):
     print x, y

will print something like

f f
o o
o o
b b
a z
r r

> for x in xrange(0, len(bar[0])):
>     print bar[0][x], bar[1][x]    #yes I realize there's no comparison here,
> I know how to do that - this is just a placeholder

Not entirely valid in this case, but the pythonic way to have a value as well 
as its index is by using the enumerate() function:

for idx, val in ['A', 'B', 'C']:
     print idx, val

will print something like

0 A
1 B
2 C

Good luck,

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