# Levenshtein distance (v21)

## Setup

``````function levenshtein_distance_a (a, b) {
if(a.length == 0) return b.length;
if(b.length == 0) return a.length;

var matrix = [];

// increment along the first column of each row
var i;
for(i = 0; i <= b.length; i++){
matrix[i] = [i];
}

// increment each column in the first row
var j;
for(j = 0; j <= a.length; j++){
matrix[0][j] = j;
}

// Fill in the rest of the matrix
for(i = 1; i <= b.length; i++){
for(j = 1; j <= a.length; j++){
if(b.charAt(i-1) == a.charAt(j-1)){
matrix[i][j] = matrix[i-1][j-1];
} else {
matrix[i][j] = Math.min(matrix[i-1][j-1] + 1, // substitution
Math.min(matrix[i][j-1] + 1, // insertion
matrix[i-1][j] + 1)); // deletion
}
}
}

return matrix[b.length][a.length];
}

function levenshtein_distance_b (a, b) {
var matrix = [];
var i;
var j;
if(a.length === 0) return b.length;
if(b.length === 0) return a.length;
// increment along the first column of each row
for (i = 0; i <= b.length; i++){
matrix[i] = [i];
}
// increment each column in the first row
for (j = 0; j <= a.length; j++){
matrix[0][j] = j;
}
// Fill in the rest of the matrix
for (i = 1; i <= b.length; i++){
for (j = 1; j <= a.length; j++){
if (b.charAt(i-1) === a.charAt(j-1)){
matrix[i][j] = matrix[i-1][j-1];
} else {
matrix[i][j] = Math.min(matrix[i-1][j-1] + 1, // substitution
Math.min(matrix[i][j-1] + 1, // insertion
matrix[i-1][j] + 1)); // deletion
}
}
}
return matrix[b.length][a.length];
}``````

## Test runner

Testing in
TestOps/sec
algorithm A
``levenshtein_distance_a('frankenstein', 'frankestein')``
algorithm B
``levenshtein_distance_b('frankenstein', 'frankestein')``

## Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.