nlpcraft/src/main/scala/org/apache/nlpcraft/common/nlp/pos/NCPennTreebank.scala

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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
 *
 *      https://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 org.apache.nlpcraft.common.nlp.pos

import scala.collection.immutable.HashMap

/**
 * Penn Treebank POS helper.
 */
object NCPennTreebank {
    // http://www.ling.upenn.edu/courses/Fall_2003/ling001/penn_treebank_pos.html
    private final val PENN_TREEBANK = HashMap[String, String] (
        "CC" -> "Coordinating conjunction",
        "CD" -> "Cardinal number",
        "DT" -> "Determiner",
        "EX" -> "Existential there",
        "FW" -> "Foreign word",
        "IN" -> "Preposition or sub. conjunction",
        "JJ" -> "Adjective",
        "JJR" -> "Adjective, comparative",
        "JJS" -> "Adjective, superlative",
        "LS" -> "List item marker",
        "MD" -> "Modal",
        "NN" -> "Noun, singular or mass",
        "NNS" -> "Noun, plural",
        "NNP" -> "Proper noun, singular",
        "NNPS" -> "Proper noun, plural",
        "PDT" -> "Predeterminer",
        "POS" -> "Possessive ending",
        "PRP" -> "Personal pronoun",
        "PRP$" -> "Possessive pronoun",
        "RB" -> "Adverb",
        "RBR" -> "Adverb, comparative",
        "RBS" -> "Adverb, superlative",
        "RP" -> "Particle",
        "SYM" -> "Symbol",
        "TO" -> "To",
        "UH" -> "Interjection",
        "VB" -> "Verb, base form",
        "VBD" -> "Verb, past tense",
        "VBG" -> "Verb, gerund or present part",
        "VBN" -> "Verb, past participle",
        "VBP" -> "Verb, non-3rd person sing. present",
        "VBZ" -> "Verb, 3rd person sing. present",
        "WDT" -> "Wh-determiner",
        "WP" -> "Wh-pronoun",
        "WP$" -> "Possessive wh-pronoun",
        "WRB" -> "Wh-adverb"
    )

    // Synthetic token.
    final val SYNTH_POS = "---"
    final val SYNTH_POS_DESC = "Synthetic tag"

    // Useful POS tags sets.
    final val NOUNS_POS = Seq("NN", "NNS", "NNP", "NNPS")
    final val VERBS_POS = Seq("VB", "VBD", "VBG", "VBN", "VBP", "VBZ")
    final val WHS_POS = Seq("WDT", "WP", "WP$", "WRB")
    final val JJS_POS = Seq("JJ", "JJR", "JJS")

    // Accessors.
    def description(tag: String): Option[String] = if (isSynthetic(tag)) Some(SYNTH_POS_DESC) else PENN_TREEBANK.get(tag)
    def contains(tag: String): Boolean = PENN_TREEBANK.contains(tag)
    def isSynthetic(tag: String): Boolean =  tag == SYNTH_POS
}