Edit Distance: Vector

This is a small library for calculating the edit distance and edit script between two vectors. It is generic enough that you should be able to use it with vectors containing values of any type you like, with changes described by any type you like, and with costs represented by any type you like (with a few restrictions).

Installing

The edit-distance-vector package is a normal Haskell library and can be installed using the Cabal package management tool.

cabal update
cabal install edit-distance-vector

Usage

The interface to edit-distance-vector is very small; just import Data.Vector.Distance, create a Params value with the correct operations to deal with your types, and pass this to leastChanges along with your Vectors.

import qualified Data.Vector as V
import           Data.Vector.Distance

-- | Editing vectors of 'Char' values, with '(String, Int, Char)' describing
--   changes, and the additive monoid of 'Int' describing costs.
str :: Params Char (String, Int, Char) (Sum Int)
str = Params
    { equivalent = (==)
    , delete i c = ("delete", i, c)
    , insert i c = ("insert", i, c)
    , substitute i c c' = ("replace", i, c')
    , cost _ = 1
    , positionOffset (op,_,_) | op == "delete" = 0
                              | otherwise      = 1
    }

main :: IO ()
main = do
    print $ leastChanges str (V.fromList "I am thomas")
                             (V.fromList "My name is Thomas")