Build a Part-of-Speech Tagger (POS Tagger)

Question

I need to build a POS tagger in Java and need to know how to get started. Are there code examples or other resources that help illustrate how POS taggers work?

Answer 1

Try Apache OpenNLP. It includes a POS Tagger tools. You can download ready-to-use English models from here.

The documentation provides details about how to use it from a Java application. Basically you need the following:

Load the POS model

InputStream modelIn = null;

try {
  modelIn = new FileInputStream("en-pos-maxent.bin");
  POSModel model = new POSModel(modelIn);
}
catch (IOException e) {
  // Model loading failed, handle the error
  e.printStackTrace();
}
finally {
  if (modelIn != null) {
    try {
      modelIn.close();
    }
    catch (IOException e) {
    }
  }
}

Instantiate the POS tagger

POSTaggerME tagger = new POSTaggerME(model);

Execute it

String sent[] = new String[]{"Most", "large", "cities", "in", "the", "US", "had", "morning", "and", "afternoon", "newspapers", "."};          
String tags[] = tagger.tag(sent);

Note that the POS tagger expects a tokenized sentence. Apache OpenNLP also provides tools and models to help with these tasks.

If you have to train your own model refer to this documentation.