matching strings in a large set of strings

[MRAB]

Karin Lagesen wrote:
> Hello.
> 
> I have approx 83 million strings, all 14 characters long. I need to be
> able to take another string and find out whether this one is present
> within the 83 million strings.
> 
> Now, I have tried storing these strings as a list, a set and a dictionary.
> I know that finding things in a set and a dictionary is very much faster
> than working with a list, so I tried those first. However, I run out of
> memory building both the set and the dictionary, so what I seem to be left
> with is the list, and using the in method.
> 
> I imagine that there should be a faster/better way than this?
> 
You could sort the list and then use a binary chop (Google can tell you
what that is if you don't know already).