ConFoo 2025

metaphone

(PHP 4, PHP 5, PHP 7, PHP 8)

metaphoneCalculate the metaphone key of a string

Description

metaphone(string $string, int $max_phonemes = 0): string

Calculates the metaphone key of string.

Similar to soundex() metaphone creates the same key for similar sounding words. It's more accurate than soundex() as it knows the basic rules of English pronunciation. The metaphone generated keys are of variable length.

Metaphone was developed by Lawrence Philips <lphilips at verity dot com>. It is described in ["Practical Algorithms for Programmers", Binstock & Rex, Addison Wesley, 1995].

Parameters

string

The input string.

max_phonemes

This parameter restricts the returned metaphone key to max_phonemes characters in length. However, the resulting phonemes are always transcribed completely, so the resulting string length may be slightly longer than max_phonemes. The default value of 0 means no restriction.

Return Values

Returns the metaphone key as a string.

Changelog

Version Description
8.0.0 The function returned false on failure.

Examples

Example #1 metaphone() basic example

<?php
var_dump
(metaphone('programming'));
var_dump(metaphone('programmer'));
?>

The above example will output:

string(7) "PRKRMNK"
string(6) "PRKRMR"

Example #2 Using the max_phonemes parameter

<?php
var_dump
(metaphone('programming', 5));
var_dump(metaphone('programmer', 5));
?>

The above example will output:

string(5) "PRKRM"
string(5) "PRKRM"

Example #3 Using the max_phonemes parameter

In this example, metaphone() is advised to produce a string of five characters, but that would require to split the final phoneme ('x' is supposed to be transcribed to 'KS'), so the function returns a string with six characters.

<?php
var_dump
(metaphone('Asterix', 5));
?>

The above example will output:

string(6) "ASTRKS"

add a note

User Contributed Notes 4 notes

up
65
mail at spam-off dot iaindooley dot com
20 years ago
you can use the metaphone function quite effectively with phrases by taking the levenshtein distances between two metaphone codes, and then taking this as a percentage of the length of the original metaphone code. thus you can define a percentage error, (say 20%) and accept only matches that are closer than that. i've found this works quite effectively in a function i am using on my website where an album name that the user entered is verified against existing album names that may be similar. this is also an excellent way of people being able to vaguely remember a phrase and get several suggestions out of the database. so you could type "i stiched nine times" with an error percentage of, say, 50 and still get 'a stitch in time saves nine' back as a match.
up
22
Vipindas K.S
16 years ago
metaphone
=======================
The metaphone() function can be used for spelling applications.This function returns the metaphone key of the string on success, or FALSE on failure.Its main use is when you are searching a genealogy database. check to see if a metaphone search is offered. It is also useful in making/searching family tree.
Given below is a simple code that calculates and compares two strings to find whether its metaphone codes are equivalent.

html code
==========
<html>
<body>
<form action="test.php" name="test" method="get">
Name1:<input type="text" name="name1" /><br />
Name2:<input type="text" name="name2" /><br />
<input type="submit" name="submit" value="compare" />
</form>

<!--php code begins here -->

<?php
if(isset($_GET['submit']))
{
$str1 = $_GET['name1'];
$str2 = $_GET['name2'];
$meta_one=metaphone($str1);
$meta_two=metaphone($str2);
echo
"metaphone code for ".$str1." is ". $meta_one;
echo
"<br />";
echo
"metaphone code for ".$str2." is ". $meta_two."<br>";
if(
$meta_one==$meta_two)
{
echo
"metaphone codes are matching";
}
else
{
echo
"metaphone codes are not matching";
}
}
?>

</body>
</html>

Metaphone algorithm was developed by Lawrence Philips.

Lawrence Philips' RULES follow:

The 16 consonant sounds:
|--- ZERO represents "th"
|
B X S K J T F H L M N P R 0 W Y

Exceptions:

Beginning of word: "ae-", "gn", "kn-", "pn-", "wr-" ----> drop first letter
"Aebersold", "Gnagy", "Knuth", "Pniewski", "Wright"

Beginning of word: "x" ----> change to "s"
as in "Deng Xiaopeng"

Beginning of word: "wh-" ----> change to "w"
as in "Whalen"

Transformations:

B ----> B unless at the end of word after "m", as in "dumb", "McComb"

C ----> X (sh) if "-cia-" or "-ch-"
S if "-ci-", "-ce-", or "-cy-"
SILENT if "-sci-", "-sce-", or "-scy-"
K otherwise, including in "-sch-"

D ----> J if in "-dge-", "-dgy-", or "-dgi-"
T otherwise

F ----> F

G ----> SILENT if in "-gh-" and not at end or before a vowel
in "-gn" or "-gned"
in "-dge-" etc., as in above rule
J if before "i", or "e", or "y" if not double "gg"
K otherwise

H ----> SILENT if after vowel and no vowel follows
or after "-ch-", "-sh-", "-ph-", "-th-", "-gh-"
H otherwise

J ----> J

K ----> SILENT if after "c"
K otherwise

L ----> L

M ----> M

N ----> N

P ----> F if before "h"
P otherwise

Q ----> K

R ----> R

S ----> X (sh) if before "h" or in "-sio-" or "-sia-"
S otherwise

T ----> X (sh) if "-tia-" or "-tio-"
0 (th) if before "h"
silent if in "-tch-"
T otherwise

V ----> F

W ----> SILENT if not followed by a vowel
W if followed by a vowel

X ----> KS

Y ----> SILENT if not followed by a vowel
Y if followed by a vowel

Z ----> S
up
15
php at casadebender dot com
16 years ago
A double metaphone pecl module is available: http://pecl.php.net/package/doublemetaphone
up
9
Ray.Paseur often uses Gmail
11 years ago
Metaphone() apparently ignores non-English characters. Comparing Plaçe TO Place yields "PL" and "PLS." A similar result comes from soundex().
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