com.johnsnowlabs.nlp.annotators.Token2Chunk.scala Maven / Gradle / Ivy

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/*
 * Copyright 2017-2022 John Snow Labs
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.johnsnowlabs.nlp.annotators

import com.johnsnowlabs.nlp.AnnotatorType._
import com.johnsnowlabs.nlp.{Annotation, AnnotatorModel, HasSimpleAnnotate}
import org.apache.spark.ml.util.{DefaultParamsReadable, Identifiable}

/** Converts `TOKEN` type Annotations to `CHUNK` type.
  *
  * This can be useful if a entities have been already extracted as `TOKEN` and following
  * annotators require `CHUNK` types.
  *
  * ==Example==
  * {{{
  * import spark.implicits._
  * import com.johnsnowlabs.nlp.base.DocumentAssembler
  * import com.johnsnowlabs.nlp.annotators.{Token2Chunk, Tokenizer}
  *
  * import org.apache.spark.ml.Pipeline
  *
  * val documentAssembler = new DocumentAssembler()
  *   .setInputCol("text")
  *   .setOutputCol("document")
  *
  * val tokenizer = new Tokenizer()
  *   .setInputCols("document")
  *   .setOutputCol("token")
  *
  * val token2chunk = new Token2Chunk()
  *   .setInputCols("token")
  *   .setOutputCol("chunk")
  *
  * val pipeline = new Pipeline().setStages(Array(
  *   documentAssembler,
  *   tokenizer,
  *   token2chunk
  * ))
  *
  * val data = Seq("One Two Three Four").toDF("text")
  * val result = pipeline.fit(data).transform(data)
  *
  * result.selectExpr("explode(chunk) as result").show(false)
  * +------------------------------------------+
  * |result                                    |
  * +------------------------------------------+
  * |[chunk, 0, 2, One, [sentence -> 0], []]   |
  * |[chunk, 4, 6, Two, [sentence -> 0], []]   |
  * |[chunk, 8, 12, Three, [sentence -> 0], []]|
  * |[chunk, 14, 17, Four, [sentence -> 0], []]|
  * +------------------------------------------+
  * }}}
  *
  * @groupname anno Annotator types
  * @groupdesc anno
  *   Required input and expected output annotator types
  * @groupname Ungrouped Members
  * @groupname param Parameters
  * @groupname setParam Parameter setters
  * @groupname getParam Parameter getters
  * @groupname Ungrouped Members
  * @groupprio param  1
  * @groupprio anno  2
  * @groupprio Ungrouped 3
  * @groupprio setParam  4
  * @groupprio getParam  5
  * @groupdesc param
  *   A list of (hyper-)parameter keys this annotator can take. Users can set and get the
  *   parameter values through setters and getters, respectively.
  */
class Token2Chunk(override val uid: String)
    extends AnnotatorModel[Token2Chunk]
    with HasSimpleAnnotate[Token2Chunk] {

  /** Output Annotator Type : CHUNK
    *
    * @group anno
    */
  override val outputAnnotatorType: AnnotatorType = CHUNK

  /** Input Annotator Type : TOKEN
    *
    * @group anno
    */
  override val inputAnnotatorTypes: Array[String] = Array(TOKEN)

  def this() = this(Identifiable.randomUID("TOKEN2CHUNK"))

  override def annotate(annotations: Seq[Annotation]): Seq[Annotation] = {
    annotations.map { token =>
      Annotation(CHUNK, token.begin, token.end, token.result, token.metadata)
    }
  }

}

/** This is the companion object of [[Token2Chunk]]. Please refer to that class for the
  * documentation.
  */
object Token2Chunk extends DefaultParamsReadable[Token2Chunk]