fast list search?

[Phil Frost]

Perhaps the standard 'sets' module would be of use? It's implemented
with dictionaries, and seems to do the thing that is needed.

On Fri, Jun 11, 2004 at 08:06:17PM -0700, Dan Gunter wrote:
> How about using a dictionary, with the keys being the ints and the 
> values being the index in the 'list', i.e. len(dictionary). This is 
> quite fast:
> 
> >>> d = {}
> >>> for i in xrange(0,500000):
> ...     if not d.has_key(i): d[i] = len(d)
> 
> -Dan
> 
> Javier Zaragoz? Arenas wrote:
> >I think the better way is sort before the list
> >
> >
> >>>thelist.sort()
> >
> >
> >And then, a binary search
> >
> >
> >>>point_of_insertion = bisect.bisect(thelist, item)
> >>>is_present = thelist[point_of_insertion -1:point_of_insertion] == [item]
> >
> > >> if not is_present:
> >....            thelist.insert(point_of_insertion, item)
> >
> >and done!
> >
> >Fco Javier Zaragoz? Arenas
> >
> >
> >
> >"ramon aragues" <ramon.aragues at gmx.net> escribi? en el mensaje
> >news:mailman.747.1086774432.6949.python-list at python.org...
> >
> >>Hi,
> >>
> >>I?ve got a list with more than 500,000 ints. Before inserting new ints,
> >>I have to check that it doesn?t exist already in the list.
> >>
> >>Currently, I am doing the standard:
> >>
> >>if new_int not in long_list:
> >>long_list.append(new_int)
> >>
> >>
> >>but it is extremely slow... is there a faster way of doing this in python?
> >>
> >>Thanks a lot,
> >>
> >>Ramon Aragues