“无法返回空头或叶树”与CoreNLP在Android上

我想在我的Android项目中使用CoreNLP。但是当我创建一个像这样的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;
    }
}

该项目链接到以下.jar文件:

  • ejml-0.23.jar
  • 斯坦福-科伦普-3.4.1.jar
  • 斯坦福-科伦普-3.4.1-模型.jar

在我使用java 1.8.0_92的桌面java环境中,此代码可以正常运行,但是当在Android上运行代码时(编译无错误后),当NLP类实例化时,我收到错误:

由以下原因引起:java.lang.IllegalArgumentException:无法返回 null 或 leaf Tree 的 head。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$10.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)

我使用的是CoreNLP 3.4.1。它不是最新版本,但它适用于Android上的Java 7。如何在Android上正确使用CoreNLP?


答案 1

为什么会出现此问题?

我一直在寻找答案。我已经检查了罐子。有一个类。从此类中,此错误出现AbstractCollinsHeadFinder.java

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。

  1. 如果树为空,则会发生此错误。
  2. 如果树是叶,则会发生此错误。

    @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;
    }
    

资源链接:

  1. 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。在你的 setProperty(...) 中,有一些参数。也许缺少一些参数。因此,您可以按照代码创建对象。

// 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);

资源链接:

创建一个斯坦福核心NLP对象


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);
        }
    }
}

资源链接:

  1. 斯坦福大学 CoreNLP 自然语言处理工具包

答案 2

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