Regular expression on tagged words

Question

Given a string representing a sentence like this followed by tagging the string using OpenNLP.

String sentence = "His plays remain highly popular, and are constantly studied.";

I get this below. My question is how do I know apply a regular expression to it to filter out tags? What is throwing me off is the word prepended to each hyphen. If it were just tags I can do something like (VBP|VBN)+ for example, the words in front would vary.

His_PRP$ plays_NNS remain_VBP highly_RB popular,_JJ and_CC are_VBP constantly_RB studied._VBN

For example, how would I write a regular expression to keep all NN and CC ? So given the tagged string as shown above how do I get plays_NNS and_CC ?

Answer 1

I think you can use regular expressions and extract the desired substrings which matches your pattern and concatenate to get required resultant string.

 String text = "His_PRP$ plays_NNS remain_VBP highly_RB popular,_JJ and_CC are_VBP constantly_RB studied._VBN";
 String pattern = "([^\\s]+_(NNS|CC))";
 String resultText = "";

    // Create a Pattern object
    Pattern r = Pattern.compile(pattern);

    // Now create matcher object.
    Matcher m = r.matcher(text);
    while (m.find( )) 
    {
      resultText = resultText + m.group(0) + " ";
    }

    System.out.println("RESULT: " + resultText);

    /*
    #### OUTPUT #####
    RESULT: plays_NNS and_CC 
    */

Answer 2

[^\s]+_(NNS|CC)

This regular expression will help you extract only NNS and CC tags. You can play with the regexp here: https://regex101.com/r/x1VxL0/1

Answer 3

Non-regex solution using a filter method.

public static void main(String []args){

  String inputText = "His_PRP$ plays_NNS remain_VBP highly_RB popular,_JJ and_CC are_VBP constantly_RB studied._VBN";

  String[] tags = {"_NN", "_CC"};
  String[] found = filter(inputText, tags);

  for(int i = 0; i < found.length; i++){
    System.out.println(found[i]);
  }
}

private static String[] filter(String text, String[] tags){

  String[] words = text.split(" "); // Split words by spaces
  ArrayList<String> results = new ArrayList<String>();

  // Save all words that match any of the provided tags
  for(String word : words){
    for(String tag : tags){
      if(word.contains(tag)){
        results.add(word);
        break;
      }
    }
  }
  return results.toArray(new String[0]); // Return results as a string array
}

Prints to the console:

plays_NNS                                                                                                                                                           
and_CC