iterating over two arrays in parallel?

Terry Reedy tjreedy at udel.edu
Fri Aug 29 08:00:03 CEST 2008



mh at pixar.com wrote:
> I want to interate over two arrays in parallel, something like this:
> 
>     a=[1,2,3]
>     b=[4,5,6]
> 
>     for i,j in a,b:
>         print i,j
> 
> where i,j would be 1,4,    2,5,   3,6  etc.
> 
> Is this possible?

How to fish for yourself:
search 'Python loop two arrays parallel' and second hit with Google is
http://docs.python.org/tut/node7.html
which has this entry
"To loop over two or more sequences at the same time, the entries can be 
paired with the zip() function.

 >>> questions = ['name', 'quest', 'favorite color']
 >>> answers = ['lancelot', 'the holy grail', 'blue']
 >>> for q, a in zip(questions, answers):
...     print 'What is your %s?  It is %s.' % (q, a)
...	
What is your name?  It is lancelot.
What is your quest?  It is the holy grail.
What is your favorite color?  It is blue.
"

Or go to the Tutorial directly, expand the chapter headings, and notice 
that 5. Data Structures has section 5.6 Looping Techniques.

Indeed, I recommend that you read thru at least the first 9 chapters.

tjr




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