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Groups > comp.lang.python > #11590

Re: testing if a list contains a sublist

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On 2011-08-16, nn <pruebauno@latinmail.com> wrote:
> That can be easily fixed:
>
>>>> def sublist(lst1, lst2):
> 	s1 = ','.join(map(str, lst1))
> 	s2 = ','.join(map(str, lst2))
> 	return False if s2.find(s1)==-1 else True
>
>>>> sublist([1,2,3],[1,2,3,4,5])
> True
>>>> sublist([1,2,2],[1,2,3,4,5])
> False
>>>> sublist([1,2,3],[1,3,5,7])
> False
>>>> sublist([12],[1,2])
> False
>>>>

String conversion is risky:

>>> sublist(['1,2', '3,4'], [1, 2, 3, 4])
True

Since we're bike-shedding, here's my entry. It's not clear to me
if accepting iterables rather than lists is a win, but I thought,
"Why not be general if the implementation is easy?"

def is_subseq_of(x, y):
    r"""Return True if the elements in iterable x are found contiguously in
    iterable y.

    >>> is_subseq_of([], [])
    True
    >>> is_subseq_of([], [1, 2, 3])
    True
    >>> is_subseq_of([1], [1, 2, 3])
    True
    >>> is_subseq_of([1], [])
    False
    >>> is_subseq_of([4, 5], [1, 2, 3, 4, 5])
    True
    >>> is_subseq_of([1, 2], [1, 3, 2])
    False
    >>> is_subseq_of([2, 3], [1, 2, 3, 4])
    True
    >>> is_subseq_of([1, 2, 2], [1, 2, 3, 4, 5])
    False
    >>> is_subseq_of([1, 2], [1, 2])
    True
    >>> is_subseq_of([1, 2, 3], [1, 2])
    False
    >>> is_subseq_of(['1,2', '3,4'], [1, 2, 3, 4])
    False
    """
    x = tuple(x)
    ix = 0
    lenx = len(x)
    if lenx == 0:
        return True
    for elem in y:
        if x[ix] == elem:
            ix += 1
        else:
            ix = 0
        if ix == lenx:
            return True
    return False

if __name__ == '__main__':
    import doctest
    doctest.testmod()

-- 
Neil Cerutti

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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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