The Ruby Way: Solutions and Techniques in Ruby Programming, Second Edition

2.36. Calculating the Levenshtein Distance Between Two Strings

The concept of distance between strings is important in inductive learning (AI), cryptography, proteins research, and in other areas.

The Levenshtein distance is the minimum number of modifications needed to change one string into another, using three basic modification operations: del(-etion), ins(-ertion), and sub(-stitution). A substitution is also considered to be a combination of a deletion and insertion (indel).

There are various approaches to this, but we will avoid getting too technical. Suffice it to say that this Ruby implementation (in Listing 2.2) allows you to provide optional parameters to set the cost for the three types of modification operations and defaults to a ...