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