What is Soundex?

senraj · #1 (**permalink**) 04-10-2008, 06:25 AM

Hi,

hi guys please explain What is Soundex?

Jeyaseelansarc · #2 (**permalink**) 04-10-2008, 06:27 AM

Hi Senraj,
Soundex is a hashing system for english words. From an english word, you generate a letter and three numbers. that roughly describe how an given word sounds. Similar sounding words will have similar codes.

Jeyaseelansarc · #3 (**permalink**) 04-10-2008, 06:28 AM

I think in PHP we have soundex() to calculate the soundex key of a string

Jeyaseelansarc · #4 (**permalink**) 04-10-2008, 06:29 AM

The Soundex code for a name consists of a letter followed by three numbers: the letter is the first letter of the name, and the numbers encode the remaining consonants. Similar sounding consonants share the same number so, for example, the labial B, F, P and V are all encoded as 1. Vowels can affect the coding, but are never coded directly unless they appear at the start of the name.

Jeyaseelansarc · #5 (**permalink**) 04-10-2008, 06:30 AM

The exact algorithm is as follows:

1. Retain the first letter of the string
2. Remove all occurrences of the following letters, unless it is the first letter: a, e, h, i, o, u, w, y
3. Assign numbers to the remaining letters (after the first) as follows:
* b, f, p, v = 1
* c, g, j, k, q, s, x, z = 2
* d, t = 3
* l = 4
* m, n = 5
* r = 6
4. If two or more letters with the same number were adjacent in the original name (before step 1), or adjacent except for any intervening h and w (American census only), then omit all but the first.
5. Return the first four characters, right-padding with zeroes if there are fewer than four.

Jeyaseelansarc · #6 (**permalink**) 04-10-2008, 06:32 AM

In PHP Soundex keys have the property that words pronounced similarly produce the same soundex key, and can thus be used to simplify searches in databases where you know the pronunciation but not the spelling

Jeyaseelansarc · #7 (**permalink**) 04-10-2008, 06:34 AM

Soundex Examples

PHP Code:

  <?php

soundex("Euler")       == soundex("Ellery");    // E460

soundex("Gauss")       == soundex("Ghosh");     // G200

soundex("Hilbert")     == soundex("Heilbronn"); // H416

soundex("Knuth")       == soundex("Kant");      // K530

soundex("Lloyd")       == soundex("Ladd");      // L300

soundex("Lukasiewicz") == soundex("Lissajous"); // L222

?>

Kamalakannan · #8 (**permalink**) 04-10-2008, 06:38 AM

soundex()

The soundex() function calculates the soundex key of a string.

A soundex key is a four character long alphanumeric string that represent English pronunciation of a word.

The soundex() function can be used for spelling applications.

This function returns the soundex key of the string on success, or FALSE on failure.

Syntax
soundex(string)

string - Required. Specifies the string to check

Tips and Notes

Note: The soundex() function creates the same key for similar sounding words.

Tip: metaphone() is more accurate than soundex(), because metaphone() knows the basic rules of English pronunciation.

Kamalakannan · #9 (**permalink**) 04-10-2008, 06:39 AM

For Example:

PHP Code:

  <?php

$str = "hello";

echo soundex($str);

?>

Output:

PHP Code:

  H400

Kamalakannan · #10 (**permalink**) 04-10-2008, 06:41 AM

One more Example:

In this example use the soundex() function on two similar sounding words:

PHP Code:

  <?php

$str = "Sun";

$str2 = "Son";

 
echo soundex($str);

echo "<br />";

echo soundex($str2);

?>

Output:

PHP Code:

  S500

S500

Jeyaseelansarc · #11 (**permalink**) 04-11-2008, 01:44 AM

Hi,
Soundex function is built in every platforms like javascript, perl or MySql or MS Sql, etc.,

I think whoever wants to work on it then it is useful.

Any idea how it used in MySql?

Jeyaseelansarc · #12 (**permalink**) 04-14-2008, 05:13 AM

In mysql we can get soundex key as like

Code:

select soundex(name) from test

Jeyaseelansarc · #13 (**permalink**) 04-14-2008, 05:15 AM

Metaphone is a phonetic algorithm, an algorithm for indexing words by their sound, when pronounced in English. The algorithm produces variable length keys as its output, as opposed to Soundex's fixed-length keys. Similar sounding words share the same keys.

Jeyaseelansarc · #14 (**permalink**) 04-14-2008, 05:17 AM

In Javascript we won't have this actual function, but we have prototype function as:

HTML Code:

<script>
String.prototype.soundex = function(p){ //v1.0
	var i, j, r, p = isNaN(p) ? 4 : p > 10 ? 10 : p < 4 ? 4 : p,
	m = {BFPV: 1, CGJKQSXZ: 2, DT: 3, L: 4, MN: 5, R: 6},
	r = (s = this.toUpperCase().replace(/[^A-Z]/g, "").split("")).splice(0, 1);
	for(i in s)
		for(j in m)
			if(j.indexOf(s[i]) + 1 && r[r.length-1] != m[j] && r.push(m[j]))
				break;
	return r.length > p && (r.length = p), r.join("") + (new Array(p - r.length + 1)).join("0");
};
</script>

Jeyaseelansarc · #15 (**permalink**) 04-14-2008, 05:18 AM

we can use the above prototype function as

HTML Code:

<script>
alert("Jonas\nJones\nMatrix\nMaytrix".replace(/\w+/g, function(s){
	return s + " = " + s.soundex();
}));



</script>

Kamalakannan · #16 (**permalink**) 04-15-2008, 03:34 AM

Hi,

In Oracle/PLSQL, the soundex function returns a phonetic representation (the way it sounds) of a string.

syntax:

Quote:

soundex( string1 )

string1 is the string whose phonetic value will be returned.

Kamalakannan · #17 (**permalink**) 04-15-2008, 03:35 AM

The Soundex algorithm is as follows:

1. The soundex return value will always begin with the first letter of string1.
2. The soundex function uses only the first 5 consonants to determine the NUMERIC portion of the return value, except if the first letter of string1 is a vowel.
3. The soundex function is not case-sensitive. What this means is that both uppercase and lowercase characters will generate the same soundex return value.

Applies To:

* Oracle 8i, Oracle 9i, Oracle 10g, Oracle 11g

Kamalakannan · #18 (**permalink**) 04-15-2008, 03:38 AM

For Example:

Quote:

soundex('tech on the net');
soundex('TECH ON THE NET');
soundex('apples');
soundex('apples are great');
soundex('applus');

Return output as below:

Quote:

'T253'
'T253'
'A142'
'A142'
'A142'

Jeyaseelansarc · #19 (**permalink**) 04-22-2008, 02:10 AM

in PERL As the soundex algorithm was originally used a long time ago in the US it considers only the English alphabet and pronunciation. In particular, non-ASCII characters will be ignored. The recommended method of dealing with characters that have accents, or other unicode characters, is to use the Text::Unidecode module available from CPAN.

Jeyaseelansarc · #20 (**permalink**) 04-22-2008, 02:11 AM

example in PERL

Code:

use Text::Soundex;

  # Original algorithm.
  $code = soundex($name);    # Get the soundex code for a name.
  @codes = soundex(@names);  # Get the list of codes for a list of names.

  # American Soundex variant (NARA) - Used for US census data.
  $code = soundex_nara($name);    # Get the soundex code for a name.
  @codes = soundex_nara(@names);  # Get the list of codes for a list of names.

  # Redefine the value that soundex() will return if the input string
  # contains no identifiable sounds within it.
  $Text::Soundex::nocode = 'Z000';

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode