在 Android 上使用 CoreNLP，“不能 return 空树或叶树的头部”

Question

我想在我的 Android 项目中使用 CoreNLP。但是当我像这样创建一个 CoreNLP 实例时：

import java.util.Properties;
import edu.stanford.nlp.ling.CoreAnnotations;
import edu.stanford.nlp.neural.rnn.RNNCoreAnnotations;
import edu.stanford.nlp.pipeline.Annotation;
import edu.stanford.nlp.pipeline.StanfordCoreNLP;
import edu.stanford.nlp.sentiment.SentimentCoreAnnotations;
import edu.stanford.nlp.trees.Tree;
import edu.stanford.nlp.util.CoreMap;

public class NLP {

    private StanfordCoreNLP pipeline;
    Properties props;

    public NLP() {
        props = new Properties();
        props.setProperty("annotators", "tokenize, ssplit, pos, parse, sentiment");
        pipeline = new StanfordCoreNLP(props);//-->ERROR, SEE BELOW
    }

    public int findSentiment(String line) {
        int mainSentiment = 0;
        if (line != null && line.length() > 0) {
            int longest = 0;
            Annotation annotation = pipeline.process(line);
            for (CoreMap sentence : annotation
                    .get(CoreAnnotations.SentencesAnnotation.class)) {
                Tree tree = sentence
                        .get(SentimentCoreAnnotations.AnnotatedTree.class);
                int sentiment = RNNCoreAnnotations.getPredictedClass(tree);
                String partText = sentence.toString();
                if (partText.length() > longest) {
                    mainSentiment = sentiment;
                    longest = partText.length();
                }

            }
        }
        return mainSentiment;
    }
}

项目链接到以下 .jar 文件：

ejml-0.23.jar
stanford-corenlp-3.4.1.jar
stanford-corenlp-3.4.1-models.jar

在我的桌面 java 环境中 java 1.8.0_92，此代码运行正确，但是当运行 Android 上的代码（编译无误后），实例化 NLP class 时出现错误：

Caused by: java.lang.IllegalArgumentException: Can't return head of null or leaf Tree. at edu.stanford.nlp.trees.AbstractCollinsHeadFinder.determineHead(AbstractCollinsHeadFinder.java:158) at edu.stanford.nlp.trees.AbstractCollinsHeadFinder.determineHead(AbstractCollinsHeadFinder.java:138) at edu.stanford.nlp.pipeline.ParserAnnotator.(ParserAnnotator.java:132) at edu.stanford.nlp.pipeline.AnnotatorImplementations.parse(AnnotatorImplementations.java:132) at edu.stanford.nlp.pipeline.StanfordCoreNLP.create(StanfordCoreNLP.java:719) at edu.stanford.nlp.pipeline.AnnotatorPool.get(AnnotatorPool.java:85) at edu.stanford.nlp.pipeline.StanfordCoreNLP.construct(StanfordCoreNLP.java:292) at edu.stanford.nlp.pipeline.StanfordCoreNLP.(StanfordCoreNLP.java:129) at edu.stanford.nlp.pipeline.StanfordCoreNLP.(StanfordCoreNLP.java:125)

我正在使用 CoreNLP 3.4.1。它不是最新版本，但它适用于 Java 7 on Android。如何在 Android 上正确使用 CoreNLP？

Answer 1

为什么会出现这个问题？

我一直在寻找答案。我检查了罐子。有一个classAbstractCollinsHeadFinder.java。从这个class，这个错误就来了

edu.stanford.nlp.trees.AbstractCollinsHeadFinder.determineHead(AbstractCollinsHeadFinder.java:158) at edu.stanford.nlp.trees.AbstractCollinsHeadFinder.determineHead(AbstractCollinsHeadFinder.java:138)

此错误有 2 个根本原因。

如果树为空，则会发生此错误。

如果树是叶子，就会出现这个错误。

@Override
public Tree determineHead(Tree t, Tree parent) {
  if (nonTerminalInfo == null) {
    throw new IllegalStateException("Classes derived from AbstractCollinsHeadFinder must create and fill HashMap nonTerminalInfo.");
  }
  // The error mainly generate for the following condition
  if (t == null || t.isLeaf()) {
    throw new IllegalArgumentException("Can't return head of null or leaf Tree."); 
  }
  if (DEBUG) {
    log.info("determineHead for " + t.value());
  }

  Tree[] kids = t.children();
  -------------
  -------------
  return theHead;
}

资源Link：

https://github.com/stanfordnlp/CoreNLP/blob/master/src/edu/stanford/nlp/trees/AbstractCollinsHeadFinder.java#L163

检查参数：

我也检查了你的代码。在您的 setProperty(...) 中，有一些参数。 可能缺少一些参数。因此，您可以按照代码创建一个对象。

// creates a StanfordCoreNLP object, with POS tagging, lemmatization, NER, parsing, and coreference resolution 
Properties props = new Properties();
props.setProperty("annotators", "tokenize, ssplit, pos, lemma, ner, parse, dcoref");
StanfordCoreNLP pipeline = new StanfordCoreNLP(props);

资源Link：

creates a StanfordCoreNLP object

一个简单、完整的示例程序：

import java.io.*;
import java.util.*;
import edu.stanford.nlp.io.*;
import edu.stanford.nlp.ling.*;
import edu.stanford.nlp.pipeline.*;
import edu.stanford.nlp.trees.*;
import edu.stanford.nlp.trees.TreeCoreAnnotations.*;
import edu.stanford.nlp.util.*;

public class StanfordCoreNlpExample {
    public static void main(String[] args) throws IOException {
        PrintWriter xmlOut = new PrintWriter("xmlOutput.xml");
        Properties props = new Properties();
        props.setProperty("annotators",
                "tokenize, ssplit, pos, lemma, ner, parse");
        StanfordCoreNLP pipeline = new StanfordCoreNLP(props);
        Annotation annotation = new Annotation(
                "This is a short sentence. And this is another.");
        pipeline.annotate(annotation);
        pipeline.xmlPrint(annotation, xmlOut);
        // An Annotation is a Map and you can get and use the
        // various analyses individually. For instance, this
        // gets the parse tree of the 1st sentence in the text.
        List<CoreMap> sentences = annotation
                .get(CoreAnnotations.SentencesAnnotation.class);
        if (sentences != null && sentences.size() > 0) {
            CoreMap sentence = sentences.get(0);
            Tree tree = sentence.get(TreeAnnotation.class);
            PrintWriter out = new PrintWriter(System.out);
            out.println("The first sentence parsed is:");
            tree.pennPrint(out);
        }
    }
}

资源Link：

The Stanford CoreNLP Natural Language Processing Toolkit

在 Android 上使用 CoreNLP，“不能 return 空树或叶树的头部”

'Can't return head of null or leaf Tree' with CoreNLP on Android

java

android

stanford-nlp

sentiment-analysis

为什么会出现这个问题？

资源Link：

检查参数：

资源Link：

一个简单、完整的示例程序：

资源Link：