From: Nuralanur@...
Date: 2005-09-27T07:46:05+09:00
Subject: In search of a kind of converse to sub/gsub

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Dear all,
 
while reading the thread about ggsub, I recalled a problem I have tried  to
code but stopped for lack of time.
Now, if you can't do it yourself, why not let others work for you ;-)  ?
 
When correcting a text for typos, one can minimize the Levenstein  distance
(number of character changes from one string to  another)  of the mis-spelled 
word
to a list of correctly-spelled words.
However, many words are short, and there are a lot of "correct",  English 
words you can produce by, say, changing three letters in a  three-letter word.
Yet typos are much more specific - there are essentially inversions 'ab'  
->'ba'
or misspellings coming from hitting nearby keys on the keyboard.
 
Now I am too lazy to identify all these possibilities and I am searching  for 
some method of the form
 
class String
    def find_what_to_replace(other)
            ...
            return  replace_what_substring,replace_by
    end
end
 
such that  for
 
replace_what_substring,replace_it_by  =string1.find_what_to_replace(string2)
 
the statement
 
string2 == string1.gsub(replace_what_substring,replace_it_by)
 
holds true .
 
Has anybody done that already?
 
Best regards,
 
Axel
 

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