Function: soundex

soundex is a byte-compiled function defined in soundex.el.gz.

Signature

(soundex WORD)

Documentation

Return a Soundex key for WORD.

Implemented as described in: Knuth, Donald E. "The Art of Computer Programming, Vol. 3: Sorting and Searching", Addison-Wesley (1973), pp. 391-392.

Source Code

;; Defined in /usr/src/emacs/lisp/soundex.el.gz
(defun soundex (word)
  "Return a Soundex key for WORD.
Implemented as described in:
Knuth, Donald E. \"The Art of Computer Programming, Vol. 3: Sorting
and Searching\", Addison-Wesley (1973), pp. 391-392."
  (let* ((word (upcase word)) (length (length word))
	 (code (cdr (assq (aref word 0) soundex-alist)))
	 (key (substring word 0 1)) (index 1) (prev-code code))
    ;; once we have a four char key, we're done
    (while (and (> 4 (length key)) (< index length))
      ;; look up the code for each letter in word at index
      (setq code (cdr (assq (aref word index) soundex-alist))
	    index (1+ index)
	    ;; append code to key unless the same codes belong to
	    ;; adjacent letters in the original string
	    key (concat key (if (or (null code) (string= code prev-code))
				()
			      code))
	    prev-code code))
    ;; return a key that is 4 chars long and padded by "0"s if needed
    (if (> 4 (length key))
	(substring (concat key "000") 0 4)
      key)))