is there a better way?

[Steve Holden]

markscala at gmail.com wrote:
> Problem:
> 
> You have a list of unknown length, such as this: list =
> [X,X,X,O,O,O,O].  You want to extract all and only the X's.  You know
> the X's are all up front and you know that the item after the last X is
> an O, or that the list ends with an X.  There are never O's between
> X's.
> 
> I have been using something like this:
> _____________________
> 
> while list[0] != O:
>     storage.append(list[0])
>     list.pop(0)
>     if len(list) == 0:
>         break
> _____________________
> 
> But this seems ugly to me, and using "while" give me the heebies.  Is
> there a better approach?
> 
> hope this is clear.

  >>> X = "X"
  >>> O = "O"
  >>> def fl(l):
  ...   for i, v in enumerate(l):
  ...     if v == O:
  ...       return l[:i]
  ...   return l
  ...
  >>> fl([X,X,X,X,O,O,O])
['X', 'X', 'X', 'X']
  >>> fl([])
[]
  >>> fl([O])
[]
  >>> fl([X])
['X']
  >>>

regards
  Steve
-- 
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