A PNL de Stanford, demonstrada aqui , fornece uma saída como esta:

Colorless/JJ green/JJ ideas/NNS sleep/VBP furiously/RB ./.

O que significam as tags Part of Speech? Não consigo encontrar uma lista oficial. É o próprio sistema de Stanford ou eles estão usando tags universais? (O que é JJ, por exemplo?)

Além disso, quando estou percorrendo as frases, procurando substantivos, por exemplo, acabo fazendo algo como verificar se a tag .contains('N'). Isso parece muito fraco. Existe uma maneira melhor de procurar programaticamente uma determinada parte do discurso?

O Projeto Penn Treebank . Veja a marcação de parte do discurso ps.

JJ é adjetivo. NNS é substantivo, plural. VBP é verbo no tempo presente. RB é advérbio.

Isso é para inglês. Para os chineses, é o Penn Chinese Treebank. E para o alemão é o corpus da NEGRA.

1. Conjunto de coordenação do CC
2. CD Cardinal number
3. DT Determiner
4. EX Existencial lá
5. Palavra estrangeira FW
6. IN Preposição ou conjunção subordinada
7. JJ Adjective
8. JJR Adjetivo, comparativo
9. JJS Adjetivo, superlativo
10. Marcador de item de lista LS
11. MD Modal
12. NN Substantivo ou singular
13. Substantivo NNS
14. NNP Nome próprio, singular
15. NNPS Nome próprio, plural
16. PDT Predeterminer
17. POS Possível final
18. PRP Pronome pessoal
19. PRP $ Pronome possessivo
20. RB Adverb
21. RBR Advérbio, comparativo
22. Advérbio RBS, superlativo
23. RP Particle
24. Símbolo SYM
25. TO para
26. Interjeição UH
27. VB Verb, formulário base
28. VBD Verbo, pretérito
29. VBG Verbo, gerúndio ou particípio presente
30. VBN Verbo, particípio passado
31. VBP Verb, presente na 3ª pessoa do singular
32. VBZ Verb, terceira pessoa do singular do presente
33. WDT Whdeterminer
34. WP Whpronoun
35. WP $ Nome possuído
36. WRB Whadverb

Explanation of each tag from the documentation :

CC: conjunction, coordinating
    & 'n and both but either et for less minus neither nor or plus so
    therefore times v. versus vs. whether yet
CD: numeral, cardinal
    mid-1890 nine-thirty forty-two one-tenth ten million 0.5 one forty-
    seven 1987 twenty '79 zero two 78-degrees eighty-four IX '60s .025
    fifteen 271,124 dozen quintillion DM2,000 ...
DT: determiner
    all an another any both del each either every half la many much nary
    neither no some such that the them these this those
EX: existential there
    there
FW: foreign word
    gemeinschaft hund ich jeux habeas Haementeria Herr K'ang-si vous
    lutihaw alai je jour objets salutaris fille quibusdam pas trop Monte
    terram fiche oui corporis ...
IN: preposition or conjunction, subordinating
    astride among uppon whether out inside pro despite on by throughout
    below within for towards near behind atop around if like until below
    next into if beside ...
JJ: adjective or numeral, ordinal
    third ill-mannered pre-war regrettable oiled calamitous first separable
    ectoplasmic battery-powered participatory fourth still-to-be-named
    multilingual multi-disciplinary ...
JJR: adjective, comparative
    bleaker braver breezier briefer brighter brisker broader bumper busier
    calmer cheaper choosier cleaner clearer closer colder commoner costlier
    cozier creamier crunchier cuter ...
JJS: adjective, superlative
    calmest cheapest choicest classiest cleanest clearest closest commonest
    corniest costliest crassest creepiest crudest cutest darkest deadliest
    dearest deepest densest dinkiest ...
LS: list item marker
    A A. B B. C C. D E F First G H I J K One SP-44001 SP-44002 SP-44005
    SP-44007 Second Third Three Two * a b c d first five four one six three
    two
MD: modal auxiliary
    can cannot could couldn't dare may might must need ought shall should
    shouldn't will would
NN: noun, common, singular or mass
    common-carrier cabbage knuckle-duster Casino afghan shed thermostat
    investment slide humour falloff slick wind hyena override subhumanity
    machinist ...
NNS: noun, common, plural
    undergraduates scotches bric-a-brac products bodyguards facets coasts
    divestitures storehouses designs clubs fragrances averages
    subjectivists apprehensions muses factory-jobs ...
NNP: noun, proper, singular
    Motown Venneboerger Czestochwa Ranzer Conchita Trumplane Christos
    Oceanside Escobar Kreisler Sawyer Cougar Yvette Ervin ODI Darryl CTCA
    Shannon A.K.C. Meltex Liverpool ...
NNPS: noun, proper, plural
    Americans Americas Amharas Amityvilles Amusements Anarcho-Syndicalists
    Andalusians Andes Andruses Angels Animals Anthony Antilles Antiques
    Apache Apaches Apocrypha ...
PDT: pre-determiner
    all both half many quite such sure this
POS: genitive marker
    ' 's
PRP: pronoun, personal
    hers herself him himself hisself it itself me myself one oneself ours
    ourselves ownself self she thee theirs them themselves they thou thy us
PRP$: pronoun, possessive
    her his mine my our ours their thy your
RB: adverb
    occasionally unabatingly maddeningly adventurously professedly
    stirringly prominently technologically magisterially predominately
    swiftly fiscally pitilessly ...
RBR: adverb, comparative
    further gloomier grander graver greater grimmer harder harsher
    healthier heavier higher however larger later leaner lengthier less-
    perfectly lesser lonelier longer louder lower more ...
RBS: adverb, superlative
    best biggest bluntest earliest farthest first furthest hardest
    heartiest highest largest least less most nearest second tightest worst
RP: particle
    aboard about across along apart around aside at away back before behind
    by crop down ever fast for forth from go high i.e. in into just later
    low more off on open out over per pie raising start teeth that through
    under unto up up-pp upon whole with you
SYM: symbol
    % & ' '' ''. ) ). * + ,. < = > @ A[fj] U.S U.S.S.R * ** ***
TO: "to" as preposition or infinitive marker
    to
UH: interjection
    Goodbye Goody Gosh Wow Jeepers Jee-sus Hubba Hey Kee-reist Oops amen
    huh howdy uh dammit whammo shucks heck anyways whodunnit honey golly
    man baby diddle hush sonuvabitch ...
VB: verb, base form
    ask assemble assess assign assume atone attention avoid bake balkanize
    bank begin behold believe bend benefit bevel beware bless boil bomb
    boost brace break bring broil brush build ...
VBD: verb, past tense
    dipped pleaded swiped regummed soaked tidied convened halted registered
    cushioned exacted snubbed strode aimed adopted belied figgered
    speculated wore appreciated contemplated ...
VBG: verb, present participle or gerund
    telegraphing stirring focusing angering judging stalling lactating
    hankerin' alleging veering capping approaching traveling besieging
    encrypting interrupting erasing wincing ...
VBN: verb, past participle
    multihulled dilapidated aerosolized chaired languished panelized used
    experimented flourished imitated reunifed factored condensed sheared
    unsettled primed dubbed desired ...
VBP: verb, present tense, not 3rd person singular
    predominate wrap resort sue twist spill cure lengthen brush terminate
    appear tend stray glisten obtain comprise detest tease attract
    emphasize mold postpone sever return wag ...
VBZ: verb, present tense, 3rd person singular
    bases reconstructs marks mixes displeases seals carps weaves snatches
    slumps stretches authorizes smolders pictures emerges stockpiles
    seduces fizzes uses bolsters slaps speaks pleads ...
WDT: WH-determiner
    that what whatever which whichever
WP: WH-pronoun
    that what whatever whatsoever which who whom whosoever
WP$: WH-pronoun, possessive
    whose
WRB: Wh-adverb
    how however whence whenever where whereby whereever wherein whereof why

A resposta aceita acima está faltando as seguintes informações:

Também há 9 tags de pontuação definidas (que não estão listadas em algumas referências, veja aqui ). Esses são:

1. #
2. $
3. '' (usado para todas as formas de cotação de fechamento)
4. ((usado para todas as formas de parênteses de abertura)
5. ) (usado para todas as formas de fechamento entre parênteses)
6. ,
7. . (usado para toda a pontuação de finalização de sentença)
8. : (usado para dois pontos, ponto e vírgula e elipses)
9. `` (usado para todas as formas de cotação de abertura)

Aqui está uma lista mais completa de tags para o Penn Treebank (postada aqui para fins de completude):

http://www.surdeanu.info/mihai/teaching/ista555-fall13/readings/PennTreebankConstituents.html

Ele também inclui tags para níveis de cláusula e frase.

Nível da cláusula

- S
- SBAR
- SBARQ
- SINV
- SQ

Nível da frase

- ADJP
- ADVP
- CONJP
- FRAG
- INTJ
- LST
- NAC
- NP
- NX
- PP
- PRN
- PRT
- QP
- RRC
- UCP
- VP
- WHADJP
- WHAVP
- WHNP
- WHPP
- X

(descrições no link)

Apenas no caso de você querer codificá-lo ...

/**
 * Represents the English parts-of-speech, encoded using the
 * de facto <a href="http://www.cis.upenn.edu/~treebank/">Penn Treebank
 * Project</a> standard.
 * 
 * @see <a href="ftp://ftp.cis.upenn.edu/pub/treebank/doc/tagguide.ps.gz">Penn Treebank Specification</a>
 */
public enum PartOfSpeech {
  ADJECTIVE( "JJ" ),
  ADJECTIVE_COMPARATIVE( ADJECTIVE + "R" ),
  ADJECTIVE_SUPERLATIVE( ADJECTIVE + "S" ),

  /* This category includes most words that end in -ly as well as degree
   * words like quite, too and very, posthead modi ers like enough and
   * indeed (as in good enough, very well indeed), and negative markers like
   * not, n't and never.
   */
  ADVERB( "RB" ),

  /* Adverbs with the comparative ending -er but without a strictly comparative
   * meaning, like <i>later</i> in <i>We can always come by later</i>, should
   * simply be tagged as RB.
   */
  ADVERB_COMPARATIVE( ADVERB + "R" ),
  ADVERB_SUPERLATIVE( ADVERB + "S" ),

  /* This category includes how, where, why, etc.
   */
  ADVERB_WH( "W" + ADVERB ),

  /* This category includes and, but, nor, or, yet (as in Y et it's cheap,
   * cheap yet good), as well as the mathematical operators plus, minus, less,
   * times (in the sense of "multiplied by") and over (in the sense of "divided
   * by"), when they are spelled out. <i>For</i> in the sense of "because" is
   * a coordinating conjunction (CC) rather than a subordinating conjunction.
   */
  CONJUNCTION_COORDINATING( "CC" ),
  CONJUNCTION_SUBORDINATING( "IN" ),
  CARDINAL_NUMBER( "CD" ),
  DETERMINER( "DT" ),

  /* This category includes which, as well as that when it is used as a
   * relative pronoun.
   */
  DETERMINER_WH( "W" + DETERMINER ),
  EXISTENTIAL_THERE( "EX" ),
  FOREIGN_WORD( "FW" ),

  LIST_ITEM_MARKER( "LS" ),

  NOUN( "NN" ),
  NOUN_PLURAL( NOUN + "S" ),
  NOUN_PROPER_SINGULAR( NOUN + "P" ),
  NOUN_PROPER_PLURAL( NOUN + "PS" ),

  PREDETERMINER( "PDT" ),
  POSSESSIVE_ENDING( "POS" ),

  PRONOUN_PERSONAL( "PRP" ),
  PRONOUN_POSSESSIVE( "PRP$" ),

  /* This category includes the wh-word whose.
   */
  PRONOUN_POSSESSIVE_WH( "WP$" ),

  /* This category includes what, who and whom.
   */
  PRONOUN_WH( "WP" ),

  PARTICLE( "RP" ),

  /* This tag should be used for mathematical, scientific and technical symbols
   * or expressions that aren't English words. It should not used for any and
   * all technical expressions. For instance, the names of chemicals, units of
   * measurements (including abbreviations thereof) and the like should be
   * tagged as nouns.
   */
  SYMBOL( "SYM" ),
  TO( "TO" ),

  /* This category includes my (as in M y, what a gorgeous day), oh, please,
   * see (as in See, it's like this), uh, well and yes, among others.
   */
  INTERJECTION( "UH" ),

  VERB( "VB" ),
  VERB_PAST_TENSE( VERB + "D" ),
  VERB_PARTICIPLE_PRESENT( VERB + "G" ),
  VERB_PARTICIPLE_PAST( VERB + "N" ),
  VERB_SINGULAR_PRESENT_NONTHIRD_PERSON( VERB + "P" ),
  VERB_SINGULAR_PRESENT_THIRD_PERSON( VERB + "Z" ),

  /* This category includes all verbs that don't take an -s ending in the
   * third person singular present: can, could, (dare), may, might, must,
   * ought, shall, should, will, would.
   */
  VERB_MODAL( "MD" ),

  /* Stanford.
   */
  SENTENCE_TERMINATOR( "." );

  private final String tag;

  private PartOfSpeech( String tag ) {
    this.tag = tag;
  }

  /**
   * Returns the encoding for this part-of-speech.
   * 
   * @return A string representing a Penn Treebank encoding for an English
   * part-of-speech.
   */
  public String toString() {
    return getTag();
  }

  protected String getTag() {
    return this.tag;
  }

  public static PartOfSpeech get( String value ) {
    for( PartOfSpeech v : values() ) {
      if( value.equals( v.getTag() ) ) {
        return v;
      }
    }

    throw new IllegalArgumentException( "Unknown part of speech: '" + value + "'." );
  }
}

Estou fornecendo a lista completa aqui e também fornecendo link de referência

1.  CC   Coordinating conjunction
2.  CD   Cardinal number
3.  DT   Determiner
4.  EX   Existential there
5.  FW   Foreign word
6.  IN   Preposition or subordinating conjunction
7.  JJ   Adjective
8.  JJR  Adjective, comparative
9.  JJS  Adjective, superlative
10. LS   List item marker
11. MD   Modal
12. NN   Noun, singular or mass
13. NNS  Noun, plural
14. NNP  Proper noun, singular
15. NNPS Proper noun, plural
16. PDT  Predeterminer
17. POS  Possessive ending
18. PRP  Personal pronoun
19. PRP$ Possessive pronoun
20. RB   Adverb
21. RBR  Adverb, comparative
22. RBS  Adverb, superlative
23. RP   Particle
24. SYM  Symbol
25. TO   to
26. UH   Interjection
27. VB   Verb, base form
28. VBD  Verb, past tense
29. VBG  Verb, gerund or present participle
30. VBN  Verb, past participle
31. VBP  Verb, non-3rd person singular present
32. VBZ  Verb, 3rd person singular present
33. WDT  Wh-determiner
34. WP   Wh-pronoun
35. WP$  Possessive wh-pronoun
36. WRB  Wh-adverb

Você pode descobrir a lista completa de tags Parts of Speech aqui .

Com relação à sua segunda questão de encontrar uma determinada palavra / bloco com a tag POS (por exemplo, Substantivo), aqui está o código de exemplo que você pode seguir.

public static void main(String[] args) {
    Properties properties = new Properties();
    properties.put("annotators", "tokenize, ssplit, pos, lemma, ner, parse");
    StanfordCoreNLP pipeline = new StanfordCoreNLP(properties);

    String input = "Colorless green ideas sleep furiously.";
    Annotation annotation = pipeline.process(input);
    List<CoreMap> sentences = annotation.get(CoreAnnotations.SentencesAnnotation.class);
    List<String> output = new ArrayList<>();
    String regex = "([{pos:/NN|NNS|NNP/}])"; //Noun
    for (CoreMap sentence : sentences) {
        List<CoreLabel> tokens = sentence.get(CoreAnnotations.TokensAnnotation.class);
        TokenSequencePattern pattern = TokenSequencePattern.compile(regex);
        TokenSequenceMatcher matcher = pattern.getMatcher(tokens);
        while (matcher.find()) {
            output.add(matcher.group());
        }
    }
    System.out.println("Input: "+input);
    System.out.println("Output: "+output);
}

A saída é:

Input: Colorless green ideas sleep furiously.
Output: [ideas]

Eles parecem ser tags Brown Corpus .

Stanford CoreNLP Tags para outros idiomas: francês, espanhol, alemão ...

Vejo que você usa o analisador para o idioma inglês, que é o modelo padrão. Você pode usar o analisador para outros idiomas (francês, espanhol, alemão ...) e esteja ciente de que os tokenizadores e parte dos marcadores de fala são diferentes para cada idioma. Se você quiser fazer isso, deverá fazer o download do modelo específico para o idioma (usando um construtor como o Maven, por exemplo) e, em seguida, definir o modelo que deseja usar. Aqui você tem mais informações sobre isso.

Aqui estão as listas de tags para diferentes idiomas:

1. Stanford CoreNLP POS Tags para espanhol
2. O Stanford CoreNLP POS Tagger para alemão usa o conjunto de tags Stuttgart-Tübingen (STTS)
3. O etiquetador POS Stanford CoreNLP para francês usa as seguintes tags:

ETIQUETAS PARA FRANCÊS:

Parte das etiquetas de fala para francês

A     (adjective)
Adv   (adverb)
CC    (coordinating conjunction)
Cl    (weak clitic pronoun)
CS    (subordinating conjunction)
D     (determiner)
ET    (foreign word)
I     (interjection)
NC    (common noun)
NP    (proper noun)
P     (preposition)
PREF  (prefix)
PRO   (strong pronoun)
V     (verb)
PONCT (punctuation mark)

Tags de categorias frasais para francês:

AP     (adjectival phrases)
AdP    (adverbial phrases)
COORD  (coordinated phrases)
NP     (noun phrases)
PP     (prepositional phrases)
VN     (verbal nucleus)
VPinf  (infinitive clauses)
VPpart (nonfinite clauses)
SENT   (sentences)
Sint, Srel, Ssub (finite clauses)

Funções sintáticas para francês:

SUJ    (subject)
OBJ    (direct object)
ATS    (predicative complement of a subject)
ATO    (predicative complement of a direct object)
MOD    (modifier or adjunct)
A-OBJ  (indirect complement introduced by à)
DE-OBJ (indirect complement introduced by de)
P-OBJ  (indirect complement introduced by another preposition)

Em spacy, foi muito rápido, eu acho, em apenas um notebook de baixo custo, ele será executado assim:

import spacy
import time

start = time.time()

with open('d:/dictionary/e-store.txt') as f:
    input = f.read()

word = 0
result = []

nlp = spacy.load("en_core_web_sm")
doc = nlp(input)

for token in doc:
    if token.pos_ == "NOUN":
        result.append(token.text)
    word += 1

elapsed = time.time() - start

print("From", word, "words, there is", len(result), "NOUN found in", elapsed, "seconds")

A saída em várias tentativas:

From 3547 words, there is 913 NOUN found in 7.768507719039917 seconds
From 3547 words, there is 913 NOUN found in 7.408619403839111 seconds
From 3547 words, there is 913 NOUN found in 7.431427955627441 seconds

Então, acho que você não precisa se preocupar com o loop de cada verificação de tag POS :)

Mais melhorias que tive quando desabilitei um determinado pipeline:

nlp = spacy.load("en_core_web_sm", disable = 'ner')

Então, o resultado é mais rápido:

From 3547 words, there is 913 NOUN found in 6.212834596633911 seconds
From 3547 words, there is 913 NOUN found in 6.257707595825195 seconds
From 3547 words, there is 913 NOUN found in 6.371225833892822 seconds