Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!news-out.readnews.com!transit3.readnews.com!panix!not-for-mail
From: Grant Edwards <invalid@invalid.invalid>
Newsgroups: comp.lang.python
Subject: Re: looking for a neat solution to a nested loop problem
Date: Mon, 6 Aug 2012 19:22:55 +0000 (UTC)
Organization: PANIX Public Access Internet and UNIX, NYC
Lines: 54
Message-ID: <jvp5if$m3q$1@reader1.panix.com>
References: <a8a7hvF8crU1@mid.individual.net> <pan.2012.08.06.16.18.08.86000@nowhere.com> <a8acciFcukU1@mid.individual.net> <jvp25t$k8e$1@reader1.panix.com> <jvp2eb$k8e$2@reader1.panix.com> <a8aio3Ftq2U1@mid.individual.net>
NNTP-Posting-Host: dsl.comtrol.com
X-Trace: reader1.panix.com 1344280975 22650 64.122.56.22 (6 Aug 2012 19:22:55 GMT)
X-Complaints-To: abuse@panix.com
NNTP-Posting-Date: Mon, 6 Aug 2012 19:22:55 +0000 (UTC)
User-Agent: slrn/pre1.0.0-18 (Linux)
Xref: csiph.com comp.lang.python:26649

On 2012-08-06, Tom P <werotizy@freent.dd> wrote:

>>>> 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)
>
>   ah, that looks good - I guess it works in 2.x as well?

I don't know.  Let me test that for you...

   $ python
   Python 2.6.8 (unknown, May 18 2012, 11:56:26) 
   [GCC 4.5.3] on linux2
   Type "help", "copyright", "credits" or "license" for more information.
   >>> from itertools import chain
   >>> for i in chain(range(0,5),range(5,10)):
   ...   print i
   ... 
   0
   1
   2
   3
   4
   5
   6
   7
   8
   9
   >>> 

Yes, it works in 2.x as well.

-- 
Grant Edwards               grant.b.edwards        Yow! ... bleakness
                                  at               ... desolation ... plastic
                              gmail.com            forks ...