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names commonly found in the United States. It improves encoding for proper names in particular to a considerable extent. The author claims that in general it improves accuracy for all words from the approximately 89% of Double
Metaphone to 98%. Developers can also now set switches in code to cause the algorithm to encode Metaphone keys 1) taking non-initial vowels into account, as well as 2) encoding voiced and unvoiced consonants differently. This allows the result set to be more closely focused if the developer finds that the search results include too many words that don't resemble the search term closely enough. Metaphone 3 is sold as C++, Java, C#, PHP, Perl, and PL/SQL source, Ruby and Python wrappers accessing a Java jar, and also Metaphone 3 for Spanish and German pronunciation available as Java and C# source. The latest revision of the Metaphone 3 algorithm is v2.5.4, released March 2015. The Metaphone3 Java source code for an earlier version, 2.1.3, lacking a large number of encoding corrections made in the current version, version 2.5.4, was included as part of the OpenRefine project and is publicly viewable.
45:. Contrary to the original algorithm whose application is limited to English only, this version takes into account spelling peculiarities of a number of other languages. In 2009 Philips released a third version, called Metaphone 3, which achieves an accuracy of approximately 99% for English words, non-English words familiar to Americans, and first names and family names commonly found in the United States, having been developed according to modern engineering standards against a test harness of prepared correct encodings.
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the same as 'D'. Consider, also, that all
English speakers often pronounce 'Z' where 'S' is spelled, almost always when a noun ending in a voiced consonant or a liquid is pluralized, for example "seasons", "beams", "examples", etc. Not encoding vowels after an initial vowel sound will help to group words where a vowel and a consonant may be transposed in the misspelling or alternative pronunciation.
284:
This approximate encoding is necessary to account for the way
English speakers vary their pronunciations and misspell or otherwise vary words and names they are trying to spell. Vowels, of course, are notoriously highly variable. British speakers often complain that Americans seem to pronounce 'T's
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To implement
Metaphone without purchasing a (source code) copy of Metaphone 3, the reference implementation of Double Metaphone can be used. Alternatively, version 2.1.3 of Metaphone 3, an earlier 2009 version without a number of encoding corrections made in the current version, version 2.5.4, has
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A professional version was released in
October 2009, developed by the same author, Lawrence Philips. It is a commercial product sold as source code. Metaphone 3 further improves phonetic encoding of words in the English language, non-English words familiar to Americans, and first names and family
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algorithm by using information about variations and inconsistencies in
English spelling and pronunciation to produce a more accurate encoding, which does a better job of matching words and names which sound similar. As with Soundex, similar-sounding words should share the same keys. Metaphone is
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This table does not constitute a complete description of the original
Metaphone algorithm, and the algorithm cannot be coded correctly from it. Original Metaphone contained many errors and was superseded by Double Metaphone, and in turn Double Metaphone and original Metaphone were superseded by
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It is called "Double" because it can return both a primary and a secondary code for a string; this accounts for some ambiguous cases as well as for multiple variants of surnames with common ancestry. For example, encoding the name "Smith" yields a primary code of
94:'C' transforms to 'X' if followed by 'IA' or 'H' (unless in latter case, it is part of '-SCH-', in which case it transforms to 'K'). 'C' transforms to 'S' if followed by 'I', 'E', or 'Y'. Otherwise, 'C' transforms to 'K'.
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words that start with a vowel sound will have an 'A', representing any vowel, as the first character of the encoding (in Double
Metaphone and Metaphone 3 - original Metaphone just preserves the actual vowel),
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languages. On the other hand, rough phonetic encoding causes language dependency — or, in a language variant, average language-speaker dependency — mainly for non-English variants.
229:, and other origins. Thus it uses a much more complex ruleset for coding than its predecessor; for example, it tests for approximately 100 different contexts of the use of the letter C alone.
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The Double
Metaphone phonetic encoding algorithm is the second generation of this algorithm. Its implementation was described in the June 2000 issue of
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voiced/unvoiced consonant pairs will be mapped to the same encoding. (Examples of voiced/unvoiced consonant pairs are D/T, B/P, Z/S, G/K, etc.).
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AEIOU are also used, but only at the beginning of the code. This table summarizes most of the rules in the original implementation:
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Drop 'G' if followed by 'H' and 'H' is not at the end or before a vowel. Drop 'G' if followed by 'N' or 'NED' and is at the end.
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33:, published by Lawrence Philips in 1990, for indexing words by their English pronunciation. It fundamentally improves on the
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There are some misconceptions about the
Metaphone algorithms that should be addressed. The following statements are true:
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103:'G' transforms to 'J' if before 'I', 'E', or 'Y', and it is not in 'GG'. Otherwise, 'G' transforms to 'K'.
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121:'T' transforms to 'X' if followed by 'IA' or 'IO'. 'TH' transforms to '0'. Drop 'T' if followed by 'CH'.
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produce phonetic representations of the input words and names; rather, the output is an intentionally
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Metaphone 3, which corrects thousands of miscodings that will be produced by the first two versions.
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Hanging on the Metaphone, Lawrence Philips. Computer Language, Vol. 7, No. 12 (December), 1990.
166:. It makes a number of fundamental design improvements over the original Metaphone algorithm.
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97:'D' transforms to 'J' if followed by 'GE', 'GY', or 'GI'. Otherwise, 'D' transforms to 'T'.
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All of them are designed to address regular, "dictionary" words, not just names, and
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127:'WH' transforms to 'W' if at the beginning. Drop 'W' if not followed by a vowel.
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130:'X' transforms to 'S' if at the beginning. Otherwise, 'X' transforms to 'KS'.
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479:"Best Faces Forward: A Large-scale Study of People Search in the Enterprise"
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Perhaps the first example of stable adaptation of non-English metaphone was
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vowels after an initial vowel sound will be disregarded and not encoded, and
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If the word begins with 'KN', 'GN', 'PN', 'AE', 'WR', drop the first letter.
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Metaphone for Brazilian Portuguese, in C with PHP and PostgreSQL port.
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Guy, Ido; Ur, Sigalit; Ronen, Inbal; Weber, Sara; Oral, Tolga (2012).
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Philips later produced a new version of the algorithm, which he named
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77:", and the others represent their usual English pronunciations. The
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19:"Lawrence Philips" redirects here. For the football player, see
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Double Metaphone tries to account for myriad irregularities in
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available as a built-in operator in a number of systems.
118:'S' transforms to 'X' if followed by 'H', 'IO', or 'IA'.
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New York State Identification and Intelligence System
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phonetic representation, according to this standard:
178:, while the name "Schmidt" yields a primary code of
591:, By Lawrence Phillips, June 1, 2000, Dr Dobb's,
106:Drop 'H' if after vowel and not before a vowel.
320:municipality of Brazil, and it evolved to the
297:and other languages, having been preferred to
85:Drop duplicate adjacent letters, except for C.
57:symbols 0BFHJKLMNPRSTWXY. The '0' represents "
91:Drop 'B' if after 'M' at the end of the word.
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613:Metaphone for Brazilian Portuguese, in Java.
148:been made available under the terms of the
139:Drop all vowels unless it is the beginning.
599:Metaphone algorithms for other languages
512:"Lawrence Philips' Metaphone Algorithm"
456:"The double metaphone search algorithm"
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627:Double Metaphone algorithm for Amharic
622:Double Metaphone algorithm for Bangla
589:The Double Metaphone Search Algorithm
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16:Phonetic algorithm for indexing words
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133:Drop 'Y' if not followed by a vowel.
53:Original Metaphone codes use the 16
562:"OpenRefine source for Metaphone3"
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454:Philips, Lawrence (June 2000).
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611:Brazilian Portuguese in Java
289:Metaphone of other languages
152:via the OpenRefine project.
617:Spanish Metaphone in Python
405:Philips, Lawrence (1999) .
353:Approximate string matching
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537:"Anthropomorphic Software"
316:as a database solution in
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632:Russian Metaphone in Ruby
605:Brazilian Portuguese in C
381:"Morfoedro - Technology"
293:Metaphone is useful for
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182:and a secondary code of
174:and a secondary code of
112:'PH' transforms to 'F'.
109:'CK' transforms to 'K'.
136:'Z' transforms to 'S'.
124:'V' transforms to 'F'.
115:'Q' transforms to 'K'.
348:Match Rating Approach
242:Common misconceptions
310:Brazilian Portuguese
658:Phonetic algorithms
491:on December 1, 2023
460:C/C++ Users Journal
314:originated in ~2008
163:C/C++ Users Journal
69:), 'X' represents "
407:"Double Metaphone"
156:Double Metaphone
31:phonetic algorithm
541:www.amorphics.com
510:Atkinson, Kevin.
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466:(6): 38–43.
301:in several
259:approximate
233:Metaphone 3
190:in common.
186:—both have
150:BSD License
566:github.com
516:aspell.net
414:GNU Aspell
359:References
338:Caverphone
642:Metaphone
326:algorithm
61:" (as an
55:consonant
49:Procedure
27:Metaphone
652:Category
332:See also
322:current
203:Germanic
299:Soundex
227:Chinese
223:Spanish
219:Italian
195:English
35:Soundex
546:16 May
521:16 May
440:GitHub
390:16 May
215:French
207:Celtic
199:Slavic
79:vowels
73:" or "
571:2 Nov
489:(PDF)
482:(PDF)
410:(CPP)
312:: it
211:Greek
63:ASCII
29:is a
640:and
573:2020
548:2018
523:2018
497:2024
421:2024
392:2018
255:not
197:of
188:XMT
184:SMT
180:XMT
176:XMT
172:SM0
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67:Θ
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