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Soundex

Problem

You want to generate Soundex hashes of surnames, for doing "sounds-like" indexing databases, or retrieving information from the US Census records and similar pre-existing databases.

Soundex is a string hash historically used by the US Census for indexing surnames by a function of what they "sound" like, rather than their precise spelling. Further general information on Soundex is available at http://www.archives.gov/research_room/genealogy/census/soundex.html.

Solution

Use the soundex.scm library by NeilVanDyke, which can be installed? via a .plt file available from http://www.neilvandyke.org/soundex-scm/.

Specify the PLT module form of soundex.scm with like:

(require (lib "soundex.ss" "soundex"))

(Most non-PLT Scheme implementations can use the load procedure or other facility to load the file soundex.scm.)

Soundex keys are represented as four-character strings:

> (soundex "Smith")
"S530"
> (soundex "Smyth")
"S530"

Therefore, the equal? procedure can be used to compare Soundex keys:

> (equal? (soundex "Johnson") (soundex "Jackson"))
#f
> (equal? (soundex "Johnson") (soundex "JANZEN"))
#t

Both current NARA Soundex and "old" Soundex are supported (soundex is an alias for soundex-nara):

> (soundex-nara "Ashcraft")
"A261"
> (soundex-old "Ashcraft")
"A226"

Multiple Soundex keys based on prefix-skipping can be generated with the soundex-nara/prefixing, soundex-old/prefixing, and soundex/p procedures:

> (soundex/p "vanderlinden")
("V536" "D645" "L535")

Discussion

Discussion here

See Also