Comparing 2 similar strings?

[Don]

William Park wrote:

> How do you compare 2 strings, and determine how much they are "close" to
> each other?  Eg.
>     aqwerty
>     qwertyb
> are similar to each other, except for first/last char.  But, how do I
> quantify that?
> 
> I guess you can say for the above 2 strings that
>     - at max, 6 chars out of 7 are same sequence --> 85% max
> 
> But, for
>     qawerty
>     qwerbty
> max correlation is
>     - 3 chars out of 7 are the same sequence --> 42% max
> 
> (Crossposted to 3 of my favourite newsgroup.)
> 

http://www.personal.psu.edu/staff/i/u/iua1/python/apse/
http://www.nist.gov/dads/HTML/editDistance.html