Question

I’m using levenshtein algorithm to meet these requirements:

When finding a word of N characters, the words to suggest as correction in my dictionary database are:

Every dictionary word of N characters that has 1 character of difference with the found word. Example: found word:bearn, dictionary word: bears

Every dictionary word of N+1 characters that has N characters equal to the found word. Example: found word:bear, dictionary word: bears

Every dictionary word of N-1 characters that has N-1 characters equal to the found word. Example: found word: bears, dictionary word: bear

I’m using this implementation of Levenshtein algorithm in C++ to find when a word has a Levenshtein number of 1 (which is the Levenshtein number for all three cases), but then how do I choose the word to suggest? I read about Boyer-Moore-Horspool and Knuth-Morris-Pratt but I’m not sure on how either of them can be helpful.

#include <string> #include <vector> #include <algorithm>  using namespace std;  int levenshtein(const string &s1, const string &s2) {    string::size_type N1 = s1.length();    string::size_type N2 = s2.length();    string::size_type i, j;    vector<int> T(N2+1);     for ( i = 0; i <= N2; i++ )       T[i] = i;     for ( i = 0; i < N1; i++ ) {       T[0] = i+1;       int corner = i;       for ( j = 0; j < N2; j++ ) {          int upper = T[j+1];          if ( s1[i] == s2[j] )             T[j+1] = corner;          else             T[j+1] = min(T[j], min(upper, corner)) + 1;          corner = upper;       }    }    return T[N2]; } 

Answer 1

You may also want to add Norvig’s excellent article on spelling correction to your reading.

It’s been a while since I’ve read it but I remember it being very similar to what your writing about.