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Re: testing if a list contains a sublist

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>> hi list,
>> what is the best way to check if a given list (lets call it l1) is
>> totally contained in a second list (l2)?
>>
>> for example:
>> l1 = [1,2], l2 = [1,2,3,4,5] ->  l1 is contained in l2
>> l1 = [1,2,2,], l2 = [1,2,3,4,5] ->  l1 is not contained in l2
>> l1 = [1,2,3], l2 = [1,3,5,7] ->  l1 is not contained in l2
>>
>> my problem is the second example, which makes it impossible to work with
>> sets insteads of lists. But something like set.issubset for lists would
>> be nice.
>>
>> greatz Johannes
Fastest, error-free and simplest solution is to use sets:

 >>> l1 = [1,2]
 >>> l2 = [1,2,3,4,5]
 >>> set(l1)-set(l2)
set([])
 >>> set(l2)-set(l1)
set([3, 4, 5])
 >>>

Although with big lists, this is not very memory efficient. But I must 
tell you, sometimes I use this method for lists with millions of 
integers, and it is very fast and reliable, and memory is not a concern 
for me, at least - some million integers will fit into a few MB of 
memory. Read the docs about set operators  for creating union, symmetric 
difference etc.

Best,

    Laszlo

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testing if a list contains a sublist Johannes <dajo.mail@web.de> - 2011-08-16 01:26 +0200
  Re: testing if a list contains a sublist Roy Smith <roy@panix.com> - 2011-08-15 20:53 -0400
    Re: testing if a list contains a sublist Laszlo Nagy <gandalf@shopzeus.com> - 2011-08-16 08:51 +0200
      Re: testing if a list contains a sublist alex23 <wuwei23@gmail.com> - 2011-08-16 00:19 -0700
      Re: testing if a list contains a sublist alex23 <wuwei23@gmail.com> - 2011-08-16 00:14 -0700
        Re: testing if a list contains a sublist Laszlo Nagy <gandalf@shopzeus.com> - 2011-08-16 10:00 +0200
        Re: testing if a list contains a sublist Johannes <dajo.mail@web.de> - 2011-08-16 17:26 +0200
      Re: testing if a list contains a sublist ChasBrown <cbrown@cbrownsystems.com> - 2011-08-16 00:24 -0700
    Re: testing if a list contains a sublist Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-08-16 14:23 +0200
      Re: testing if a list contains a sublist Roy Smith <roy@panix.com> - 2011-08-16 08:53 -0400
      Re: testing if a list contains a sublist nn <pruebauno@latinmail.com> - 2011-08-16 07:53 -0700
        Re: testing if a list contains a sublist Laszlo Nagy <gandalf@shopzeus.com> - 2011-08-16 17:17 +0200
          Re: testing if a list contains a sublist Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2011-08-16 17:39 +0200
        Re: testing if a list contains a sublist Neil Cerutti <neilc@norwich.edu> - 2011-08-16 17:45 +0000
  Re: testing if a list contains a sublist Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-16 12:12 +1000
    Re: testing if a list contains a sublist Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-16 18:19 +1000
  Re: testing if a list contains a sublist ChasBrown <cbrown@cbrownsystems.com> - 2011-08-15 23:14 -0700
  Re: testing if a list contains a sublist ChasBrown <cbrown@cbrownsystems.com> - 2011-08-15 23:13 -0700
  Re: testing if a list contains a sublist ChasBrown <cbrown@cbrownsystems.com> - 2011-08-15 23:14 -0700
    Re: testing if a list contains a sublist Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-16 18:37 +1000
      Re: testing if a list contains a sublist ChasBrown <cbrown@cbrownsystems.com> - 2011-08-16 21:13 -0700
  Re: testing if a list contains a sublist Nobody <nobody@nowhere.com> - 2011-08-16 12:21 +0100
    Re: testing if a list contains a sublist John Posner <jjposner@codicesoftware.com> - 2011-08-16 09:57 -0400
    Re: testing if a list contains a sublist John Posner <jjposner@optimum.net> - 2011-08-16 09:57 -0400
      Re: testing if a list contains a sublist Nobody <nobody@nowhere.com> - 2011-08-17 13:28 +0100
  Re: testing if a list contains a sublist Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-08-20 12:10 +1000

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