fuzzy_distance_dam - BigQuery

SELECT `justfunctions.eu.fuzzy_distance_dam`("pyhtno", "python")
                                            
/*--Output--
2
*/

CREATE OR REPLACE FUNCTION `your_project_id.your_dataset_id.fuzzy_distance_dam`(`string_1` STRING, `string_2` STRING) RETURNS INT64
	LANGUAGE js AS r'''const initMatrix = (string_1, string_2) => {
  if (undefined == string_1 || undefined == string_2) {
    return null;
  }
  let d = [];
  for (let i = 0; i <= string_1.length; i++) {
    d[i] = [];
    d[i][0] = i;
  }
  for (let j = 0; j <= string_2.length; j++) {
    d[0][j] = j;
  }
  return d;
};
const damerau = (i, j, string_1, string_2, d, cost) => {
  if (i > 1 && j > 1 && string_1[i - 1] === string_2[j - 2] && string_1[i - 2] === string_2[j - 1]) {
    d[i][j] = Math.min.apply(null, [d[i][j], d[i - 2][j - 2] + cost]);
  }
};
if (
  undefined == string_1 ||
  undefined == string_2 ||
  "string" !== typeof string_1 ||
  "string" !== typeof string_2
) {
  return -1;
}
let d = initMatrix(string_1, string_2);
if (null === d) {
  return -1;
}
for (var i = 1; i <= string_1.length; i++) {
  let cost;
  for (let j = 1; j <= string_2.length; j++) {
    if (string_1.charAt(i - 1) === string_2.charAt(j - 1)) {
      cost = 0;
    } else {
      cost = 1;
    }
    d[i][j] = Math.min.apply(null, [
      d[i - 1][j] + 1,
      d[i][j - 1] + 1,
      d[i - 1][j - 1] + cost
    ]);
    damerau(i, j, string_1, string_2, d, cost);
  }
}
return d[string_1.length][string_2.length];''' OPTIONS ( description = '''Calculates Damerau-Levenshtein distance between <string_1> and <string_2>.'''  )

JavaScript User Defined Function (JavaScript UDF)