stringmetric

String metrics and phonetic algorithms for Scala. The library provides facilities to perform approximate string matching, measurement of string similarity/distance, indexing by word pronunciation, and sounds-like comparisons. In addition to the core library, each metric and algorithm has a command line interface.

• Requirements: Scala 2.10+
• Documentation: Scaladoc
• Issues: Enhancements, Questions, Bugs
• Versioning: Semantic Versioning v2.0

Metrics and algorithms

• __Dice / Sorensen__ (Similarity metric)
• Double Metaphone (Queued phonetic metric and algorithm)
• __Hamming__ (Similarity metric)
• __Jaccard__ (Similarity metric)
• __Jaro__ (Similarity metric)
• __Jaro-Winkler__ (Similarity metric)
• __Levenshtein__ (Similarity metric)
• Metaphone (Phonetic metric and algorithm)
• Monge-Elkan (Queued similarity metric)
• Match Rating Approach (Queued phonetic metric and algorithm)
• __Needleman-Wunch__ (Queued similarity metric)
• N-Gram (Similarity metric)
• NYSIIS (Phonetic metric and algorithm)
• __Overlap__ (Similarity metric)
• Ratcliff-Obershelp (Similarity metric)
• Refined NYSIIS (Phonetic metric and algorithm)
• Refined Soundex (Phonetic metric and algorithm)
• __Tanimoto__ (Queued similarity metric)
• __Tversky__ (Queued similarity metric)
• __Smith-Waterman__ (Queued similarity metric)
• Soundex (Phonetic metric and algorithm)
• Weighted Levenshtein (Similarity metric)

Depending upon

SBT:

libraryDependencies += "com.rockymadden.stringmetric" %% "stringmetric-core" % "0.27.4"

Gradle:

compile 'com.rockymadden.stringmetric:stringmetric-core_2.10:0.27.4'

Maven:

<dependency>
    <groupId>com.rockymadden.stringmetric</groupId>
    <artifactId>stringmetric-core_2.10</artifactId>
    <version>0.27.4</version>
</dependency>

Similarity package

Useful for approximate string matching and measurement of string distance. Most metrics calculate the similarity of two strings as a double with a value between 0 and 1. A value of 0 being completely different and a value of 1 being completely similar.

Dice / Sorensen Metric:

DiceSorensenMetric(1).compare("night", "nacht") // 0.6
DiceSorensenMetric(1).compare("context", "contact") // 0.7142857142857143

^{Note you must specify the size of the n-gram you wish to use.}

Hamming Metric:

HammingMetric.compare("toned", "roses") // 3
HammingMetric.compare("1011101", "1001001") // 2

^{Note the exception of integers, rather than doubles, being returned.}

Jaccard Metric:

JaccardMetric(1).compare("night", "nacht") // 0.3
JaccardMetric(1).compare("context", "contact") // 0.35714285714285715

^{Note you must specify the size of the n-gram you wish to use.}

Jaro Metric:

JaroMetric.compare("dwayne", "duane") // 0.8222222222222223
JaroMetric.compare("jones", "johnson") // 0.7904761904761904
JaroMetric.compare("fvie", "ten") // 0.0

Jaro-Winkler Metric:

JaroWinklerMetric.compare("dwayne", "duane") // 0.8400000000000001
JaroWinklerMetric.compare("jones", "johnson") // 0.8323809523809523
JaroWinklerMetric.compare("fvie", "ten") // 0.0

Levenshtein Metric:

LevenshteinMetric.compare("sitting", "kitten") // 3
LevenshteinMetric.compare("cake", "drake") // 2

^{Note the exception of integers, rather than doubles, being returned.}

N-Gram Metric:

NGramMetric(1).compare("night", "nacht") // 0.6
NGramMetric(2).compare("night", "nacht") // 0.25
NGramMetric(2).compare("context", "contact") // 0.5

^{Note you must specify the size of the n-gram you wish to use.}

Overlap Metric:

OverlapMetric(1).compare("night", "nacht") // 0.6
OverlapMetric(1).compare("context", "contact") // 0.7142857142857143

^{Note you must specify the size of the n-gram you wish to use.}

Ratcliff/Obershelp Metric:

RatcliffObershelpMetric.compare("aleksander", "alexandre") // 0.7368421052631579
RatcliffObershelpMetric.compare("pennsylvania", "pencilvaneya") // 0.6666666666666666

Weighted Levenshtein Metric:

WeightedLevenshteinMetric(10, 0.1, 1).compare("book", "back") // 2
WeightedLevenshteinMetric(10, 0.1, 1).compare("hosp", "hospital") // 0.4
WeightedLevenshteinMetric(10, 0.1, 1).compare("hospital", "hosp") // 40

^{Note you must specify the weight of each operation. Delete, insert, and then substitute. Note that while a double is returned, it can be outside the range of 0 to 1, based upon the weights used.}

Phonetic package

Useful for indexing by word pronunciation and performing sounds-like comparisons. All metrics return a boolean value indicating if the two strings sound the same, per the algorithm used. All metrics have an algorithm counterpart which provide the means to perform indexing by word pronunciation.

Metaphone Metric:

MetaphoneMetric.compare("merci", "mercy") // true
MetaphoneMetric.compare("dumb", "gum") // false

Metaphone Algorithm:

MetaphoneAlgorithm.compute("dumb") // tm
MetaphoneAlgorithm.compute("knuth") // n0

NYSIIS Metric:

NysiisMetric.compare("ham", "hum") // true
NysiisMetric.compare("dumb", "gum") // false

NYSIIS Algorithm:

NysiisAlgorithm.compute("macintosh") // mcant
NysiisAlgorithm.compute("knuth") // nnat

Refined NYSIIS Metric:

RefinedNysiisMetric.compare("ham", "hum") // true
RefinedNysiisMetric.compare("dumb", "gum") // false

Refined NYSIIS Algorithm:

RefinedNysiisAlgorithm.compute("macintosh") // mcantas
RefinedNysiisAlgorithm.compute("westerlund") // wastarlad

Refined Soundex Metric:

RefinedSoundexMetric.compare("robert", "rupert") // true
RefinedSoundexMetric.compare("robert", "rubin") // false

Refined Soundex Algorithm:

RefinedSoundexAlgorithm.compute("hairs") // h093
RefinedSoundexAlgorithm.compute("lambert") // l7081096

Soundex Metric:

SoundexMetric.compare("robert", "rupert") // true
SoundexMetric.compare("robert", "rubin") // false

Soundex Algorithm:

SoundexAlgorithm.compute("rupert") // r163
SoundexAlgorithm.compute("lukasiewicz") // l222

Convenience objects

StringAlgorithm:

StringAlgorithm.computeWithMetaphone("abcdef")
StringAlgorithm.computeWithNysiis("abcdef")

StringMetric:

StringMetric.compareWithJaccard(1)("abcdef", "abcxyz")
StringMetric.compareWithJaroWinkler("abcdef", "abcxyz")

Decorating

It is possible to decorate algorithms and metrics with additional functionality, which you can mix and match. Decorations include:

• withMemoization: Computations and comparisons are cached. Future calls made with identical arguments will be looked up, rather than computed.

• withTransform: Transform arguments prior to computation/comparison. A handful of pre-built transforms are located in the transform module.

Non-decorated:

MetaphoneAlgorithm.compute("abcdef")
MetaphoneMetric.compare("abcdef", "abcxyz")

Using memoization:

(MetaphoneAlgorithm withMemoization).compute("abcdef")

Using a transform so that we only examine alphabetical characters:

(MetaphoneAlgorithm withTransform filterAlpha).compute("abcdef")
(MetaphoneMetric withTransform filterAlpha).compare("abcdef", "abcxyz")

Using a functionally composed transform so that we only examine alphabetical characters, but the case will not matter:

val composedTransform = (filterAlpha andThen ignoreAlphaCase)

(MetaphoneAlgorithm withTransform composedTransform).compute("abcdef")
(MetaphoneMetric withTransform composedTransform).compare("abcdef", "abcxyz")

Making your own transform:

val myTransform: StringTransform = (ca) => ca.filter(_ == 'x')

(MetaphoneAlgorithm withTransform myTransform).compute("abcdef")
(MetaphoneMetric withTransform myTransform).compare("abcdef", "abcxyz")

Using memoization and a transform:

((MetaphoneAlgorithm withMemoization) withTransform filterAlpha).compute("abcdef")

Building the CLIs

$ git clone https://github.com/rockymadden/stringmetric.git
$ cd stringmetric
$ sbt clean package
$ ./project/build.sh
$ ./target/cli/jarometric abc xyz

Using the CLIs

Get help:

$ metaphonemetric --help
Compares two strings to determine if they are phonetically similarly, per the Metaphone algorithm.

Syntax:
  metaphonemetric [Options] string1 string2...

Options:
  -h, --help
    Outputs description, syntax, and options.

Get comparison value with metrics:

$ jarowinklermetric dog dawg
0.75

Get representation value with phonetic algorithms:

$ metaphonealgorithm dog
tk

License

The MIT License (MIT)

Copyright (c) 2013 Rocky Madden (http://rockymadden.com/)

Permission is hereby granted, free of charge, to any person obtaining a copy
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The above copyright notice and this permission notice shall be included in
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