Metaphone3

Metaphone3 generates two keys for a word. Two words sounds similar when either non-empty key of one word matches either of the other word’s keys. Producing keys for the words in a word list and matching them with the keys for an attempted spelling allows a spelling checker program to suggest correct spellings.

Metaphone3 is the relatively new (2010) and improved successor to Double Metaphone (1999) and Metaphone (1990).

FUNCTION	DESCRIPTION
NewMetaphone3	Returns a new metaphone3 instance with its own maximum key length. Both encodeVowels and encodeExact default to false.
Encode	Returns main and alternate keys for a word. Keys will match for similar sounding words.
SetEncodeVowels	Determines whether vowels after the first character are encoded.
SetEncodeExact	Determines whether consonants are encoded more precisely.
SetMaxLength	Sets the maximum allowed length for metaphone3 keys.
GetEncodeVowels	Returns true if vowels after the first character are encoded.
GetEncodeExact	Returns true if consonants are encoded more precisely.
GetMaxLength	Returns the maximum allowed length for metaphone3 keys.

Example use:

import "github.com/charltoncr/metaphone3"
// ...
meta := metaphone3.NewMetaphone3(4)
m, m2 := meta.Encode("knewmoanya")
n, n2 := meta.Encode("pneumonia")
if m == n || m == n2 || m2 == n || len(m2) > 0 && m2 == n2 {
    // match
}
// m is "NMN", as is n, so the two spellings match.
// The maximum allowed length for each of m, m2,
// n and n2 is 4 in this example.

Metaphone3 Convenience Functions

The Metaphone3 convenience functions ease the use of Metaphone3. Two function calls are sufficient to read all words in a file, create a map of words that have the same metaphone return values, and find all words in the map that match a given word/misspelling. See the example below.

FUNCTION/METHOD	DESCRIPTION
NewMetaphMap	Returns a MetaphMap made from a wordlist and a maximum length for the metaphone3 keys.
NewMetaphMapExact	Works like NewMetaphMap but allows control of how vowels and consonants are encoded.
NewMetaphMapFromFile	Returns a MetaphMap made from a word list file and a maximum length for the metaphone3 keys.
NewMetaphMapFromFileExact	Works like NewMetaphMapFromFile but allows control of how vowels and consonants are encoded.
AddWordsToMap	Adds words from a word list to an existing MetaphMap. This is useful for combining word lists, for example, a general word list and a user’s personal word list.
AddWordsFromFile	Adds words from a file to an existing MetaphMap.
MatchWord	Returns all words in a MetaphMap that sound like a given word. Letter case in word is ignored, as are non-alphabetic characters.
Len	Returns the number of sounds-alike keys in the metaph map.

Example use:

package main

import (
    "fmt"
    "github.com/charltoncr/metaphone3"
)
func main() {
    // The file specified by fileName should contain a comprehensive
    // word list with one word per line.  (Error check is omitted
    // for brevity.)
    fileName := "spellCheckerWords.txt" // (can be a *.txt.gz file)
    metaphMap, _ := metaphone3.NewMetaphMapFromFile(fileName, 4)
    matches := metaphMap.MatchWord("knewmoanya")
    for _, word := range matches {
        fmt.Println(word)
    }
}

Ron Charlton