Packages

class SymmetricDeleteApproach extends AnnotatorApproach[SymmetricDeleteModel] with SymmetricDeleteParams

Trains a Symmetric Delete spelling correction algorithm. Retrieves tokens and utilizes distance metrics to compute possible derived words.

The Symmetric Delete spelling correction algorithm reduces the complexity of edit candidate generation and dictionary lookup for a given Damerau-Levenshtein distance. It is six orders of magnitude faster (than the standard approach with deletes + transposes + replaces + inserts) and language independent. A dictionary of correct spellings must be provided with setDictionary either in the form of a text file or directly as an ExternalResource, where each word is parsed by a regex pattern.

Inspired by SymSpell.

For instantiated/pretrained models, see SymmetricDeleteModel.

See SymmetricDeleteModelTestSpec for further reference.

Example

In this example, the dictionary "words.txt" has the form of

...
gummy
gummic
gummier
gummiest
gummiferous
...

This dictionary is then set to be the basis of the spell checker.

import com.johnsnowlabs.nlp.base.DocumentAssembler
import com.johnsnowlabs.nlp.annotators.Tokenizer
import com.johnsnowlabs.nlp.annotators.spell.symmetric.SymmetricDeleteApproach
import org.apache.spark.ml.Pipeline

val documentAssembler = new DocumentAssembler()
  .setInputCol("text")
  .setOutputCol("document")

val tokenizer = new Tokenizer()
  .setInputCols("document")
  .setOutputCol("token")

val spellChecker = new SymmetricDeleteApproach()
  .setInputCols("token")
  .setOutputCol("spell")
  .setDictionary("src/test/resources/spell/words.txt")

val pipeline = new Pipeline().setStages(Array(
  documentAssembler,
  tokenizer,
  spellChecker
))

val pipelineModel = pipeline.fit(trainingData)
See also

NorvigSweetingApproach for an alternative approach to spell checking

ContextSpellCheckerApproach for a DL based approach

Linear Supertypes
SymmetricDeleteParams, AnnotatorApproach[SymmetricDeleteModel], CanBeLazy, DefaultParamsWritable, MLWritable, HasOutputAnnotatorType, HasOutputAnnotationCol, HasInputAnnotationCols, Estimator[SymmetricDeleteModel], PipelineStage, Logging, Params, Serializable, Identifiable, AnyRef, Any
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Inherited
  1. SymmetricDeleteApproach
  2. SymmetricDeleteParams
  3. AnnotatorApproach
  4. CanBeLazy
  5. DefaultParamsWritable
  6. MLWritable
  7. HasOutputAnnotatorType
  8. HasOutputAnnotationCol
  9. HasInputAnnotationCols
  10. Estimator
  11. PipelineStage
  12. Logging
  13. Params
  14. Serializable
  15. Identifiable
  16. AnyRef
  17. Any
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Visibility
  1. Public
  2. Protected

Instance Constructors

  1. new SymmetricDeleteApproach()
  2. new SymmetricDeleteApproach(uid: String)

Type Members

  1. type AnnotatorType = String
    Definition Classes
    HasOutputAnnotatorType

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. final def $[T](param: Param[T]): T
    Attributes
    protected
    Definition Classes
    Params
  4. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  5. def _fit(dataset: Dataset[_], recursiveStages: Option[PipelineModel]): SymmetricDeleteModel
    Attributes
    protected
    Definition Classes
    AnnotatorApproach
  6. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  7. def beforeTraining(spark: SparkSession): Unit
    Definition Classes
    AnnotatorApproach
  8. final def checkSchema(schema: StructType, inputAnnotatorType: String): Boolean
    Attributes
    protected
    Definition Classes
    HasInputAnnotationCols
  9. final def clear(param: Param[_]): SymmetricDeleteApproach.this.type
    Definition Classes
    Params
  10. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @HotSpotIntrinsicCandidate() @native()
  11. final def copy(extra: ParamMap): Estimator[SymmetricDeleteModel]
    Definition Classes
    AnnotatorApproach → Estimator → PipelineStage → Params
  12. def copyValues[T <: Params](to: T, extra: ParamMap): T
    Attributes
    protected
    Definition Classes
    Params
  13. final def defaultCopy[T <: Params](extra: ParamMap): T
    Attributes
    protected
    Definition Classes
    Params
  14. val deletesThreshold: IntParam

    Minimum frequency of corrections a word needs to have to be considered from training.

    Minimum frequency of corrections a word needs to have to be considered from training. Increase if training set is LARGE (Default: 0).

    Definition Classes
    SymmetricDeleteParams
  15. def derivedWordDistances(wordFrequencies: List[(String, Long)], maxEditDistance: Int): Map[String, (List[String], Long)]

    Computes derived words from a frequency of words

  16. val description: String

    Spell checking algorithm inspired on Symmetric Delete algorithm

    Spell checking algorithm inspired on Symmetric Delete algorithm

    Definition Classes
    SymmetricDeleteApproach → AnnotatorApproach
  17. val dictionary: ExternalResourceParam

    Optional dictionary of properly written words.

    Optional dictionary of properly written words. If provided, significantly boosts spell checking performance.

    Needs "tokenPattern" (Default: \S+) for parsing the resource.

    Example

    ...
gummy
gummic
gummier
gummiest
gummiferous
...
  18. val dupsLimit: IntParam

    Maximum duplicate of characters in a word to consider (Default: 2).

    Maximum duplicate of characters in a word to consider (Default: 2).

    Definition Classes
    SymmetricDeleteParams
  19. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  20. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  21. def explainParam(param: Param[_]): String
    Definition Classes
    Params
  22. def explainParams(): String
    Definition Classes
    Params
  23. final def extractParamMap(): ParamMap
    Definition Classes
    Params
  24. final def extractParamMap(extra: ParamMap): ParamMap
    Definition Classes
    Params
  25. final def fit(dataset: Dataset[_]): SymmetricDeleteModel
    Definition Classes
    AnnotatorApproach → Estimator
  26. def fit(dataset: Dataset[_], paramMaps: Seq[ParamMap]): Seq[SymmetricDeleteModel]
    Definition Classes
    Estimator
    Annotations
    @Since("2.0.0")
  27. def fit(dataset: Dataset[_], paramMap: ParamMap): SymmetricDeleteModel
    Definition Classes
    Estimator
    Annotations
    @Since("2.0.0")
  28. def fit(dataset: Dataset[_], firstParamPair: ParamPair[_], otherParamPairs: ParamPair[_]*): SymmetricDeleteModel
    Definition Classes
    Estimator
    Annotations
    @varargs() @Since("2.0.0")
  29. val frequencyThreshold: IntParam

    Minimum frequency of words to be considered from training.

    Minimum frequency of words to be considered from training. Increase if training set is LARGE (Default: 0).

    Definition Classes
    SymmetricDeleteParams
  30. final def get[T](param: Param[T]): Option[T]
    Definition Classes
    Params
  31. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @HotSpotIntrinsicCandidate() @native()
  32. final def getDefault[T](param: Param[T]): Option[T]
    Definition Classes
    Params
  33. def getDeletes(word: String, med: Int): List[String]

    Given a word, derive strings with up to maxEditDistance characters deleted

  34. def getDeletesThreshold: Int

    Minimum frequency of corrections a word needs to have to be considered from training.

    Minimum frequency of corrections a word needs to have to be considered from training. Increase if training set is LARGE (Default: 0).

    Definition Classes
    SymmetricDeleteParams
  35. def getDupsLimit: Int

    Maximum duplicate of characters in a word to consider (Default: 2).

    Maximum duplicate of characters in a word to consider (Default: 2).

    Definition Classes
    SymmetricDeleteParams
  36. def getFrequencyThreshold: Int

    Minimum frequency of words to be considered from training.

    Minimum frequency of words to be considered from training. Increase if training set is LARGE (Default: 0).

    Definition Classes
    SymmetricDeleteParams
  37. def getInputCols: Array[String]

    returns

    input annotations columns currently used

    Definition Classes
    HasInputAnnotationCols
  38. def getLazyAnnotator: Boolean
    Definition Classes
    CanBeLazy
  39. def getMaxEditDistance: Int

    Max edit distance characters to derive strings from a word

    Max edit distance characters to derive strings from a word

    Definition Classes
    SymmetricDeleteParams
  40. final def getOrDefault[T](param: Param[T]): T
    Definition Classes
    Params
  41. final def getOutputCol: String

    Gets annotation column name going to generate

    Gets annotation column name going to generate

    Definition Classes
    HasOutputAnnotationCol
  42. def getParam(paramName: String): Param[Any]
    Definition Classes
    Params
  43. final def hasDefault[T](param: Param[T]): Boolean
    Definition Classes
    Params
  44. def hasParam(paramName: String): Boolean
    Definition Classes
    Params
  45. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @HotSpotIntrinsicCandidate() @native()
  46. def initializeLogIfNecessary(isInterpreter: Boolean, silent: Boolean): Boolean
    Attributes
    protected
    Definition Classes
    Logging
  47. def initializeLogIfNecessary(isInterpreter: Boolean): Unit
    Attributes
    protected
    Definition Classes
    Logging
  48. val inputAnnotatorTypes: Array[AnnotatorType]

    Input annotator type : TOKEN

    Input annotator type : TOKEN

    Definition Classes
    SymmetricDeleteApproach → HasInputAnnotationCols
  49. final val inputCols: StringArrayParam

    columns that contain annotations necessary to run this annotator AnnotatorType is used both as input and output columns if not specified

    columns that contain annotations necessary to run this annotator AnnotatorType is used both as input and output columns if not specified

    Attributes
    protected
    Definition Classes
    HasInputAnnotationCols
  50. final def isDefined(param: Param[_]): Boolean
    Definition Classes
    Params
  51. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  52. final def isSet(param: Param[_]): Boolean
    Definition Classes
    Params
  53. def isTraceEnabled(): Boolean
    Attributes
    protected
    Definition Classes
    Logging
  54. val lazyAnnotator: BooleanParam
    Definition Classes
    CanBeLazy
  55. def log: Logger
    Attributes
    protected
    Definition Classes
    Logging
  56. def logDebug(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  57. def logDebug(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  58. def logError(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  59. def logError(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  60. def logInfo(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  61. def logInfo(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  62. def logName: String
    Attributes
    protected
    Definition Classes
    Logging
  63. def logTrace(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  64. def logTrace(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  65. def logWarning(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  66. def logWarning(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  67. val longestWordLength: IntParam

    Length of longest word in corpus

    Length of longest word in corpus

    Definition Classes
    SymmetricDeleteParams
  68. val maxEditDistance: IntParam

    Max edit distance characters to derive strings from a word (Default: 3)

    Max edit distance characters to derive strings from a word (Default: 3)

    Definition Classes
    SymmetricDeleteParams
  69. val maxFrequency: LongParam

    Maximum frequency of a word in the corpus

    Maximum frequency of a word in the corpus

    Definition Classes
    SymmetricDeleteParams
  70. val minFrequency: LongParam

    Minimum frequency of a word in the corpus

    Minimum frequency of a word in the corpus

    Definition Classes
    SymmetricDeleteParams
  71. def msgHelper(schema: StructType): String
    Attributes
    protected
    Definition Classes
    HasInputAnnotationCols
  72. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  73. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @HotSpotIntrinsicCandidate() @native()
  74. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @HotSpotIntrinsicCandidate() @native()
  75. def onTrained(model: SymmetricDeleteModel, spark: SparkSession): Unit
    Definition Classes
    AnnotatorApproach
  76. val optionalInputAnnotatorTypes: Array[String]
    Definition Classes
    HasInputAnnotationCols
  77. val outputAnnotatorType: AnnotatorType

    Output annotator type : TOKEN

    Output annotator type : TOKEN

    Definition Classes
    SymmetricDeleteApproach → HasOutputAnnotatorType
  78. final val outputCol: Param[String]
    Attributes
    protected
    Definition Classes
    HasOutputAnnotationCol
  79. lazy val params: Array[Param[_]]
    Definition Classes
    Params
  80. def save(path: String): Unit
    Definition Classes
    MLWritable
    Annotations
    @throws("If the input path already exists but overwrite is not enabled.") @Since("1.6.0")
  81. final def set(paramPair: ParamPair[_]): SymmetricDeleteApproach.this.type
    Attributes
    protected
    Definition Classes
    Params
  82. final def set(param: String, value: Any): SymmetricDeleteApproach.this.type
    Attributes
    protected
    Definition Classes
    Params
  83. final def set[T](param: Param[T], value: T): SymmetricDeleteApproach.this.type
    Definition Classes
    Params
  84. final def setDefault(paramPairs: ParamPair[_]*): SymmetricDeleteApproach.this.type
    Attributes
    protected
    Definition Classes
    Params
  85. final def setDefault[T](param: Param[T], value: T): SymmetricDeleteApproach.this.type
    Attributes
    protected[org.apache.spark.ml]
    Definition Classes
    Params
  86. def setDeletesThreshold(value: Int): SymmetricDeleteApproach.this.type

    Minimum frequency of corrections a word needs to have to be considered from training.

    Minimum frequency of corrections a word needs to have to be considered from training. Increase if training set is LARGE (Default: 0).

    Definition Classes
    SymmetricDeleteParams
  87. def setDictionary(path: String, tokenPattern: String = "\\S+", readAs: Format = ReadAs.TEXT, options: Map[String, String] = Map("format" -> "text")): SymmetricDeleteApproach.this.type

    Path to file with properly spelled words, tokenPattern is the regex pattern to identify them in text, readAs can be ReadAs.TEXT or ReadAs.SPARK, with options passed to Spark reader if the latter is set.

    Path to file with properly spelled words, tokenPattern is the regex pattern to identify them in text, readAs can be ReadAs.TEXT or ReadAs.SPARK, with options passed to Spark reader if the latter is set. Dictionary needs tokenPattern regex for separating words.

  88. def setDictionary(value: ExternalResource): SymmetricDeleteApproach.this.type

    External dictionary already in the form of ExternalResource, for which the Map member options has an entry defined for "tokenPattern".

    External dictionary already in the form of ExternalResource, for which the Map member options has an entry defined for "tokenPattern".

    Example

    val resource = ExternalResource(
  "src/test/resources/spell/words.txt",
  ReadAs.TEXT,
  Map("tokenPattern" -> "\\S+")
)
val spellChecker = new SymmetricDeleteApproach()
  .setInputCols("token")
  .setOutputCol("spell")
  .setDictionary(resource)
  89. def setDupsLimit(value: Int): SymmetricDeleteApproach.this.type

    Maximum duplicate of characters in a word to consider (Default: 2)

    Maximum duplicate of characters in a word to consider (Default: 2)

    Definition Classes
    SymmetricDeleteParams
  90. def setFrequencyThreshold(value: Int): SymmetricDeleteApproach.this.type

    Minimum frequency of words to be considered from training.

    Minimum frequency of words to be considered from training. Increase if training set is LARGE (Default: 0)

    Definition Classes
    SymmetricDeleteParams
  91. final def setInputCols(value: String*): SymmetricDeleteApproach.this.type
    Definition Classes
    HasInputAnnotationCols
  92. def setInputCols(value: Array[String]): SymmetricDeleteApproach.this.type

    Overrides required annotators column if different than default

    Overrides required annotators column if different than default

    Definition Classes
    HasInputAnnotationCols
  93. def setLazyAnnotator(value: Boolean): SymmetricDeleteApproach.this.type
    Definition Classes
    CanBeLazy
  94. def setLongestWordLength(value: Int): SymmetricDeleteApproach.this.type

    Length of longest word in corpus

    Length of longest word in corpus

    Definition Classes
    SymmetricDeleteParams
  95. def setMaxEditDistance(value: Int): SymmetricDeleteApproach.this.type

    Max edit distance characters to derive strings from a word

    Max edit distance characters to derive strings from a word

    Definition Classes
    SymmetricDeleteParams
  96. def setMaxFrequency(value: Long): SymmetricDeleteApproach.this.type

    Maximum frequency of a word in the corpus

    Maximum frequency of a word in the corpus

    Definition Classes
    SymmetricDeleteParams
  97. def setMinFrequency(value: Long): SymmetricDeleteApproach.this.type

    Minimum frequency of a word in the corpus

    Minimum frequency of a word in the corpus

    Definition Classes
    SymmetricDeleteParams
  98. final def setOutputCol(value: String): SymmetricDeleteApproach.this.type

    Overrides annotation column name when transforming

    Overrides annotation column name when transforming

    Definition Classes
    HasOutputAnnotationCol
  99. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  100. def toString(): String
    Definition Classes
    Identifiable → AnyRef → Any
  101. def train(dataset: Dataset[_], recursivePipeline: Option[PipelineModel]): SymmetricDeleteModel
    Definition Classes
    SymmetricDeleteApproach → AnnotatorApproach
  102. final def transformSchema(schema: StructType): StructType

    requirement for pipeline transformation validation.

    requirement for pipeline transformation validation. It is called on fit()

    Definition Classes
    AnnotatorApproach → PipelineStage
  103. def transformSchema(schema: StructType, logging: Boolean): StructType
    Attributes
    protected
    Definition Classes
    PipelineStage
    Annotations
    @DeveloperApi()
  104. val uid: String
    Definition Classes
    SymmetricDeleteApproach → Identifiable
  105. def validate(schema: StructType): Boolean

    takes a Dataset and checks to see if all the required annotation types are present.

    takes a Dataset and checks to see if all the required annotation types are present.

    schema

    to be validated

    returns

    True if all the required types are present, else false

    Attributes
    protected
    Definition Classes
    AnnotatorApproach
  106. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  107. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()
  108. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  109. def write: MLWriter
    Definition Classes
    DefaultParamsWritable → MLWritable

Deprecated Value Members

  1. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable]) @Deprecated
    Deprecated

    (Since version 9)

Inherited from SymmetricDeleteParams

Inherited from AnnotatorApproach[SymmetricDeleteModel]

Inherited from CanBeLazy

Inherited from DefaultParamsWritable

Inherited from MLWritable

Inherited from HasOutputAnnotatorType

Inherited from HasOutputAnnotationCol

Inherited from HasInputAnnotationCols

Inherited from Estimator[SymmetricDeleteModel]

Inherited from PipelineStage

Inherited from Logging

Inherited from Params

Inherited from Serializable

Inherited from Identifiable

Inherited from AnyRef

Inherited from Any

Parameters

A list of (hyper-)parameter keys this annotator can take. Users can set and get the parameter values through setters and getters, respectively.

Annotator types

Required input and expected output annotator types

Members

Parameter setters

Parameter getters