finding indices in a sequence of parentheses

[Steven Bethard]

tiissa wrote:
> I'd personnally extract the parenthesis then zip the lists of indices.
> In short:
> 
>  >>> def indices(mylist):
>  ...     lopen=reduce(list.__add__, [[i]*s.count('(') for i,s in 
> enumerate(mylist)],[])
>  ...     lclose=reduce(list.__add__, [[i]*s.count(')') for i,s in 
> enumerate(mylist)],[])
>  ...     return zip(lopen,lclose)
>  ...
>  >>> indices(lst)
>  [(2, 2), (4, 7), (6, 7), (8, 9), (8, 10)]
>  >>>

Thanks, that's a good idea.  In case anyone else is reading this thread, 
and had to mentally unwrap the reduce expressions, I believe they could 
be written as:

lopen  = [x for i, s in enumerate(lst) for x in [i]*s.count('(')]
lclose = [x for i, s in enumerate(lst) for x in [i]*s.count(')')]

or maybe:

lopen  = [i for i, s in enumerate(lst) for _ in xrange(s.count('('))]
lclose = [i for i, s in enumerate(lst) for _ in xrange(s.count(')'))]

Sorry, I have an irrational fear of reduce. ;)

STeVe