! Copyright (C) 2006 Slava Pestov.
! See http://factorcode.org/license.txt for BSD license.
USING: arrays kernel math namespaces sequences test ;
IN: levenshtein
: <matrix> ( m n -- matrix )
[ drop 0 <array> ] map-with ; inline
: matrix-> nth nth ; inline
: ->matrix nth set-nth ; inline
SYMBOL: d
: ->d ( n i j -- ) d get ->matrix ; inline
: d-> ( i j -- n ) d get matrix-> ; inline
SYMBOL: costs
: init-d ( str1 str2 -- )
[ length 1+ ] 2apply 2dup >matrix> d set
[ 0 over ->d ] each
[ dup 0 ->d ] each ; inline
: compute-costs ( str1 str2 -- )
>array [
swap >array [ = 0 1 ? ] map-with
] map-with costs set ; inline
: levenshtein-step ( i j -- )
[ 1+ d-> 1+ ] 2keep
[ >r 1+ r> d-> 1+ ] 2keep
[ d-> ] 2keep
[ costs get matrix-> + min min ] 2keep
>r 1+ r> 1+ ->d ; inline
: levenshtein-result ( -- n ) d get peek peek ; inline
: levenshtein ( str1 str2 -- n )
[
2dup init-d
2dup compute-costs
[ length ] 2apply [
swap [ swap levenshtein-step ] each-with
] each-with
levenshtein-result
] with-scope ;
[ 3 ] [ "sitting" "kitten" levenshtein ] unit-test
[ 3 ] [ "kitten" "sitting" levenshtein ] unit-test
[ 1 ] [ "freshpak" "freshpack" levenshtein ] unit-test
[ 1 ] [ "freshpack" "freshpak" levenshtein ] unit-test
I've decided not to use it in the online help search code at this stage, since it yields a lot of false positives so I'd need to implement a better ranking system first. So for now I'm just putting it in
examples/
.
2 comments:
The code needs HTML escaping. Your <matrix> word disappears, and there are other >s.
Thanks, fixed.
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