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Re: looking for a neat solution to a nested loop problem

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On 2012-08-06, Grant Edwards <invalid@invalid.invalid> wrote:
> On 2012-08-06, Tom P <werotizy@freent.dd> wrote:
>> On 08/06/2012 06:18 PM, Nobody wrote:
>>> On Mon, 06 Aug 2012 17:52:31 +0200, Tom P wrote:
>>>
>>>> consider a nested loop algorithm -
>>>>
>>>> for i in range(100):
>>>>       for j in range(100):
>>>>           do_something(i,j)
>>>>
>>>> Now, suppose I don't want to use i = 0 and j = 0 as initial values, but
>>>> some other values i = N and j = M, and I want to iterate through all
>>>> 10,000 values in sequence - is there a neat python-like way to this?
>>>
>>> 	for i in range(N,N+100):
>>> 	    for j in range(M,M+100):
>>> 	        do_something(i,j)
>>>
>>> Or did you mean something else?
>>
>> no, I meant something else ..
>>
>>    j runs through range(M, 100) and then range(0,M), and i runs through 
>> range(N,100) and then range(0,N)
>
> In 2.x:
>
>     for i in range(M,100)+range(0,M):
>         for j in range(N,100)+range(0,N):
>             do_something(i,j)
>
> Dunno if that still works in 3.x.  I doubt it, since I think in 3.x
> range returns an iterator, not?

Indeed it doesn't work in 3.x, but this does:

    from itertools import chain

    for i in chain(range(M,100),range(0,M)):
        for j in chain(range(N,100),range(0,N)):
            do_something(i,j)


-- 
Grant Edwards               grant.b.edwards        Yow! People humiliating
                                  at               a salami!
                              gmail.com            

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looking for a neat solution to a nested loop problem Tom P <werotizy@freent.dd> - 2012-08-06 17:52 +0200
  Re: looking for a neat solution to a nested loop problem John Gordon <gordon@panix.com> - 2012-08-06 16:03 +0000
    Re: looking for a neat solution to a nested loop problem Tom P <werotizy@freent.dd> - 2012-08-06 19:16 +0200
      Re: looking for a neat solution to a nested loop problem Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-07 01:27 +0000
  Re: looking for a neat solution to a nested loop problem Ian Foote <ian@feete.org> - 2012-08-06 17:07 +0100
  Re: looking for a neat solution to a nested loop problem Ethan Furman <ethan@stoneleaf.us> - 2012-08-06 09:15 -0700
  Re: looking for a neat solution to a nested loop problem Nobody <nobody@nowhere.com> - 2012-08-06 17:18 +0100
    Re: looking for a neat solution to a nested loop problem Tom P <werotizy@freent.dd> - 2012-08-06 19:14 +0200
      Re: looking for a neat solution to a nested loop problem Emile van Sebille <emile@fenx.com> - 2012-08-06 11:11 -0700
        Re: looking for a neat solution to a nested loop problem Larry Hudson <orgnut@yahoo.com> - 2012-08-06 21:02 -0700
          Re: looking for a neat solution to a nested loop problem Nobody <nobody@nowhere.com> - 2012-08-07 16:32 +0100
            Re: looking for a neat solution to a nested loop problem 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-07 18:42 -0700
            Re: looking for a neat solution to a nested loop problem 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-09 11:46 -0700
            Re: looking for a neat solution to a nested loop problem 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-09 11:39 -0700
            Re: looking for a neat solution to a nested loop problem 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-14 14:08 -0700
      Re: looking for a neat solution to a nested loop problem Grant Edwards <invalid@invalid.invalid> - 2012-08-06 18:25 +0000
        Re: looking for a neat solution to a nested loop problem Grant Edwards <invalid@invalid.invalid> - 2012-08-06 18:29 +0000
          Re: looking for a neat solution to a nested loop problem Tom P <werotizy@freent.dd> - 2012-08-06 21:03 +0200
            Re: looking for a neat solution to a nested loop problem Grant Edwards <invalid@invalid.invalid> - 2012-08-06 19:22 +0000
              Re: looking for a neat solution to a nested loop problem Emile van Sebille <emile@fenx.com> - 2012-08-06 12:52 -0700
  Re: looking for a neat solution to a nested loop problem André Malo <ndparker@gmail.com> - 2012-08-06 20:19 +0200
  Re: looking for a neat solution to a nested loop problem Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-06 15:31 -0400
  Re: looking for a neat solution to a nested loop problem Arnaud Delobelle <arnodel@gmail.com> - 2012-08-06 21:14 +0100

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