find sublist inside list

[MRAB]

Matthias Gallé wrote:
> bearophileHUGS at lycos.com wrote:
>> John O'Hagan:
>>> li=['a', 'c', 'a', 'c', 'c', 'g', 'a', 'c']
>>> for i  in range(len(li)):
>>>     if li[i:i + 2] == ['a', 'c']:
>>>         li[i:i + 2] = ['6']
>>
>> Oh well, I have done a mistake, it seems.
>> Another solution then:
>>
>>>>> 'acaccgac'.replace("ac", chr(6))
>> '\x06\x06cg\x06'
>>
>> Bye,
>> bearophile
> 
> Thanks bearophile and John for your quick answers.
> Unfortunately, the int that can replace a sublist can be > 255, but 
> John's answer looks simple and good enough for me. I will use it as a 
> starting point.
> 
John's solution changes the length of the list over which it's
iterating.

I'd suggest something more like:

     li = ['a', 'c', 'a', 'c', 'c', 'g', 'a', 'c']
     pos = 0
     try:
         while True:
             pos = li.index('a', pos)
             if li[pos : pos + 2] == ['a', 'c']:
                 li[pos : pos + 2] = [6]
             pos += 1
     except ValueError:
         pass