Class Soundex

Encodes a string into a Soundex value. Soundex is an encoding used to relate similar names, but can also be used as a general purpose scheme to find word with similar phonemes.

This class is thread-safe. Although not strictly immutable, the Lucene.Net.Analysis.Phonetic.Language.Soundex.maxLength field is not actually used.

Inheritance
System.Object
Soundex
Implements
Inherited Members
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.ToString()
Namespace: Lucene.Net.Analysis.Phonetic.Language
Assembly: Lucene.Net.Analysis.Phonetic.dll
Syntax
public class Soundex : IStringEncoder

Constructors

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Soundex()

Creates an instance using Lucene.Net.Analysis.Phonetic.Language.Soundex.US_ENGLISH_MAPPING.

Declaration
public Soundex()
See Also
Lucene.Net.Analysis.Phonetic.Language.Soundex.US_ENGLISH_MAPPING
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Soundex(Char[])

Creates a soundex instance using the given mapping. This constructor can be used to provide an internationalized mapping for a non-Western character set.

Every letter of the alphabet is "mapped" to a numerical value. This char array holds the values to which each letter is mapped. This implementation contains a default map for US_ENGLISH.

If the mapping contains an instance of SILENT_MARKER then H and W are not given special treatment.

Declaration
public Soundex(char[] mapping)
Parameters
Type Name Description
System.Char[] mapping

Mapping array to use when finding the corresponding code for a given character.
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Soundex(String)

Creates a refined soundex instance using a custom mapping. This constructor can be used to customize the mapping, and/or possibly provide an internationalized mapping for a non-Western character set.

If the mapping contains an instance of SILENT_MARKER then H and W are not given special treatment.

since 1.4

Declaration
public Soundex(string mapping)
Parameters
Type Name Description
System.String mapping

Mapping string to use when finding the corresponding code for a given character.
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Soundex(String, Boolean)

Creates a refined soundex instance using a custom mapping. This constructor can be used to customize the mapping, and/or possibly provide an internationalized mapping for a non-Western character set.

since 1.11

Declaration
public Soundex(string mapping, bool specialCaseHW)
Parameters
Type Name Description
System.String mapping

Mapping string to use when finding the corresponding code for a given character.
System.Boolean specialCaseHW

if true, then

Fields

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SILENT_MARKER

The marker character used to indicate a silent (ignored) character. These are ignored except when they appear as the first character.

Note: the US_ENGLISH_MAPPING_STRING does not use this mechanism because changing it might break existing code. Mappings that don't contain a silent marker code are treated as though H and W are silent.

To override this, use the Soundex(String, Boolean) constructor.

since 1.11

Declaration
public static readonly char SILENT_MARKER
Field Value
Type Description
System.Char
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US_ENGLISH

An instance of Soundex using the US_ENGLISH_MAPPING mapping. This treats H and W as silent letters. Apart from when they appear as the first letter, they are ignored. They don't act as separators between duplicate codes.

Declaration
public static readonly Soundex US_ENGLISH
Field Value
Type Description
Soundex
See Also
Lucene.Net.Analysis.Phonetic.Language.Soundex.US_ENGLISH_MAPPING
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US_ENGLISH_GENEALOGY

An instance of Soundex using the mapping as per the Genealogy site: http://www.genealogy.com/articles/research/00000060.html

This treats vowels (AEIOUY), H and W as silent letters. Such letters are ignored (after the first) and do not act as separators when dropping duplicate codes.

The codes for consonants are otherwise the same as for US_ENGLISH_MAPPING_STRING and US_ENGLISH_SIMPLIFIED.

since 1.11

Declaration
public static readonly Soundex US_ENGLISH_GENEALOGY
Field Value
Type Description
Soundex
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US_ENGLISH_MAPPING_STRING

This is a default mapping of the 26 letters used in US English. A value of 0 for a letter position means do not encode, but treat as a separator when it occurs between consonants with the same code.

(This constant is provided as both an implementation convenience and to allow documentation to pick up the value for the constant values page.)

Note that letters H and W are treated specially. They are ignored (after the first letter) and don't act as separators between consonants with the same code.

Declaration
public static readonly string US_ENGLISH_MAPPING_STRING
Field Value
Type Description
System.String
See Also
Lucene.Net.Analysis.Phonetic.Language.Soundex.US_ENGLISH_MAPPING
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US_ENGLISH_SIMPLIFIED

An instance of Soundex using the Simplified Soundex mapping, as described here: http://west-penwith.org.uk/misc/soundex.htm

This treats H and W the same as vowels (AEIOUY). Such letters aren't encoded (after the first), but they do act as separators when dropping duplicate codes. The mapping is otherwise the same as for US_ENGLISH.

since 1.11

Declaration
public static readonly Soundex US_ENGLISH_SIMPLIFIED
Field Value
Type Description
Soundex

Properties

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MaxLength

Gets or Sets the maxLength. Standard Soundex

Declaration
[Obsolete("This feature is not needed since the encoding size must be constant. Will be removed in 2.0.")]
public virtual int MaxLength { get; set; }
Property Value
Type Description
System.Int32

Methods

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Difference(String, String)

Encodes the strings and returns the number of characters in the two encoded strings that are the same. This return value ranges from 0 through 4: 0 indicates little or no similarity, and 4 indicates strong similarity or identical values.

See: MS T-SQL DIFFERENCE

since 1.3

Declaration
public virtual int Difference(string s1, string s2)
Parameters
Type Name Description
System.String s1

A string that will be encoded and compared.
System.String s2

A string that will be encoded and compared.
Returns
Type Description
System.Int32

The number of characters in the two encoded strings that are the same from 0 to 4.
See Also
Lucene.Net.Analysis.Phonetic.Language.SoundexUtils.Difference(Lucene.Net.Analysis.Phonetic.Language.IStringEncoder,System.String,System.String)
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Encode(String)

Encodes a string using the soundex algorithm.

Declaration
public virtual string Encode(string str)
Parameters
Type Name Description
System.String str

A string to encode.
Returns
Type Description
System.String

A Soundex code corresponding to the string supplied.
Exceptions
Type Condition
System.ArgumentException

If a character is not mapped.
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GetSoundex(String)

Retrieves the Soundex code for a given string.

Declaration
public virtual string GetSoundex(string str)
Parameters
Type Name Description
System.String str

String to encode using the Soundex algorithm.
Returns
Type Description
System.String

A soundex code for the string supplied.
Exceptions
Type Condition
System.ArgumentException

If a character is not mapped.

Implements