levenshtein.js 2.1 KB

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  1. /*
  2. Copyright (c) 2011 Andrei Mackenzie
  3. Permission is hereby granted, free of charge, to any person obtaining a copy of
  4. this software and associated documentation files (the "Software"), to deal in
  5. the Software without restriction, including without limitation the rights to
  6. use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
  7. the Software, and to permit persons to whom the Software is furnished to do so,
  8. subject to the following conditions:
  9. The above copyright notice and this permission notice shall be included in all
  10. copies or substantial portions of the Software.
  11. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  12. IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  13. FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
  14. COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
  15. IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  16. CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  17. */
  18. // levenshtein distance algorithm, pulled from Andrei Mackenzie's MIT licensed.
  19. // gist, which can be found here: https://gist.github.com/andrei-m/982927
  20. 'use strict'
  21. // Compute the edit distance between the two given strings
  22. module.exports = function levenshtein (a, b) {
  23. if (a.length === 0) return b.length
  24. if (b.length === 0) return a.length
  25. const matrix = []
  26. // increment along the first column of each row
  27. let i
  28. for (i = 0; i <= b.length; i++) {
  29. matrix[i] = [i]
  30. }
  31. // increment each column in the first row
  32. let j
  33. for (j = 0; j <= a.length; j++) {
  34. matrix[0][j] = j
  35. }
  36. // Fill in the rest of the matrix
  37. for (i = 1; i <= b.length; i++) {
  38. for (j = 1; j <= a.length; j++) {
  39. if (b.charAt(i - 1) === a.charAt(j - 1)) {
  40. matrix[i][j] = matrix[i - 1][j - 1]
  41. } else {
  42. matrix[i][j] = Math.min(matrix[i - 1][j - 1] + 1, // substitution
  43. Math.min(matrix[i][j - 1] + 1, // insertion
  44. matrix[i - 1][j] + 1)) // deletion
  45. }
  46. }
  47. }
  48. return matrix[b.length][a.length]
  49. }