Iterating two arrays at once

[mathieu]

Hi there,

  just trying to figure out how to iterate over two array without
computing the len of the array:

  A = [1,2,3]
  B = [4,5,6]
  for a,b in A,B: # does not work !
print a,b

It should print:

  1,4
  2,5
  3,6

Thanks !
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Re: Iterating two arrays at once

[Matthias Bläsing]

Am Fri, 29 Aug 2008 03:35:51 -0700 schrieb mathieu: 
   A = [1,2,3]
   B = [4,5,6]
   for a,b in A,B: # does not work !
 print a,b
 
 It should print:
 
   1,4
   2,5
   3,6

Hey,

zip is your friend:

for a,b in zip(A,B):
print a,b

does what you want. If you deal with big lists, you can use izip from 
itertools, which returns a generator.

from itertools import izip
for a,b in izip(A,B):
print a,b

HTH

Matthias
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Re: Iterating two arrays at once

[Bruno Desthuilliers]

mathieu a écrit :

Hi there,

  just trying to figure out how to iterate over two array without
computing the len of the array:

  A = [1,2,3]
  B = [4,5,6]
  for a,b in A,B: # does not work !
print a,b

It should print:

  1,4
  2,5
  3,6


for a, b in zip(A, B):
print a, b

or, using itertools (which might be a good idea if your lists are a bit 
huge):


from itertools import izip
for a, b in izip(A, B):
print a, b


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Re: Iterating two arrays at once

[mathieu]

On Aug 29, 12:46 pm, Matthias Bläsing [EMAIL PROTECTED]
aachen.de wrote:
 Am Fri, 29 Aug 2008 03:35:51 -0700 schrieb mathieu:

A = [1,2,3]
B = [4,5,6]
for a,b in A,B: # does not work !
  print a,b

  It should print:

1,4
2,5
3,6

 Hey,

 zip is your friend:

 for a,b in zip(A,B):
 print a,b

 does what you want. If you deal with big lists, you can use izip from
 itertools, which returns a generator.

 from itertools import izip
 for a,b in izip(A,B):
 print a,b

Thanks all !
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Re: Iterating two arrays at once

[Bruno Desthuilliers]

mathieu a écrit :
(snip solution)


Thanks all !


FWIW, this has been discussed here *very* recently (a couple hours ago). 
Look for a thread named iterating over two arrays in parallel?, and 
pay special attention to Terry Reedy's answer.

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