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6.9. Activity 4: Responses that Transform Statements¶

As stated previously, single keywords are interesting, but better chatbots look for groups of words. Statements like “I like cats,” “I like math class,” and “I like Spain” all have the form “I like something.” The response could be “What do you like about something?” This activity will respond to groupings of words.

Try each of the following as the value for the statement in the main method and see what they print.

I want to understand French.
Do you like me?
You confuse me.

/**
 * A program to carry on conversations with a human user.
 * This version:
 *<ul><li>
 *   Uses advanced search for keywords
 *</li><li>
 *   Will transform statements as well as react to keywords
 *</li></ul>
 * @author Laurie White
 * @version April 2012
 *
 */
public class Magpie4
{

/**
    * Get a default greeting
    * @return a greeting
    */
   public String getGreeting()
   {
      return "Hello, let's talk.";
   }

/**
    * Gives a response to a user statement
    *
    * @param statement
    *            the user statement
    * @return a response based on the rules given
    */
   public String getResponse(String statement)
   {
      String response = "";
      if (statement.length() == 0)
      {
         response = "Say something, please.";
      }

else if (findKeyword(statement, "no") >= 0)
      {
         response = "Why so negative?";
      }
      else if (findKeyword(statement, "mother") >= 0
               || findKeyword(statement, "father") >= 0
               || findKeyword(statement, "sister") >= 0
               || findKeyword(statement, "brother") >= 0)
      {
         response = "Tell me more about your family.";
      }

// Responses which require transformations
      else if (findKeyword(statement, "I want to", 0) >= 0)
      {
         response = transformIWantToStatement(statement);
      }

// Responses which require transformations
      else if (findKeyword(statement, "I want", 0) >= 0)
      {
         response = transformIWantStatement(statement);
      }

else
      {
         // Look for a two word (you <something> me)
         // pattern
         int psn = findKeyword(statement, "you", 0);

if (psn >= 0
             && findKeyword(statement, "me", psn) >= 0)
         {
            response = transformYouMeStatement(statement);
         }
         else
         {
            response = getRandomResponse();
         }
      }
      return response;
   }

/**
    * Take a statement with "I want to <something>." and transform it into
    * "What would it mean to <something>?"
    * @param statement the user statement, assumed to contain "I want to"
    * @return the transformed statement
    */
   private String transformIWantToStatement(String statement)
   {
      //  Remove the final period, if there is one
      statement = statement.trim();
      String lastChar = statement.substring(statement
                                            .length() - 1);
      if (lastChar.equals("."))
      {
         statement = statement.substring(0, statement
                                            .length() - 1);
      }
      int psn = findKeyword (statement, "I want to", 0);
      String restOfStatement = statement.substring(psn + 9).trim();
      return "What would it mean to " + restOfStatement + "?";
   }

/**
    * Take a statement with "I want <something>." and transform it into
    * Would you really be happy if you had <something>?
    * @param statement the user statement, assumed to contain "I want"
    * @return the transformed statement
    */
   private String transformIWantStatement(String statement)
   {
      //  Remove the final period, if there is one
      statement = statement.trim();
      String lastChar = statement.substring(statement
                                            .length() - 1);
      if (lastChar.equals("."))
      {
         statement = statement.substring(0, statement
                                            .length() - 1);
      }
      int psn = findKeyword (statement, "I want", 0);
      String restOfStatement = statement.substring(psn + 7);
      return "Would you really be happy if you had " + restOfStatement + "?";
   }

/**
    * Take a statement with "you <something> me" and transform it into
    * "What makes you think that I <something> you?"
    * @param statement the user statement, assumed to contain "you" followed by "me"
    * @return the transformed statement
    */
   private String transformYouMeStatement(String statement)
   {
      //  Remove the final period, if there is one
      statement = statement.trim();
      String lastChar = statement.substring(statement
                                            .length() - 1);
      if (lastChar.equals("."))
      {
         statement = statement.substring(0, statement
                                            .length() - 1);
      }

int psnOfYou = findKeyword (statement, "you", 0);
      int psnOfMe = findKeyword (statement, "me", psnOfYou + 3);

String restOfStatement = statement.substring(psnOfYou + 3, psnOfMe).trim();
      return "What makes you think that I " + restOfStatement + " you?";
   }

/**
    * Search for one word in phrase.  The search is not case sensitive.
    * This method will check that the given goal is not a substring of a longer string
    * (so, for example, "I know" does not contain "no").
    * @param statement the string to search
    * @param goal the string to search for
    * @param startPos the character of the string to begin the search at
    * @return the index of the first occurrence of goal in statement or -1 if it's not found
    */
   private int findKeyword(String statement, String goal, int startPos)
   {
      String phrase = statement.trim();
      //  The only change to incorporate the startPos is in the line below
      int psn = phrase.toLowerCase().indexOf(goal.toLowerCase(), startPos);

//  Refinement--make sure the goal isn't part of a word
      while (psn >= 0)
      {
         //  Find the string of length 1 before and after the word
         String before = " ", after = " ";
         if (psn > 0)
         {
            before = phrase.substring (psn - 1, psn).toLowerCase();
         }
         if (psn + goal.length() < phrase.length())
         {
            after = phrase.substring(psn + goal.length(), psn + goal.length() + 1).toLowerCase();
         }

//  If before and after aren't letters, we've found the word
         if (((before.compareTo ("a") < 0 ) || (before.compareTo("z") > 0))  //  before is not a letter
         && ((after.compareTo ("a") < 0 ) || (after.compareTo("z") > 0)))
         {
            return psn;
         }

//  The last position didn't work, so let's find the next, if there is one.
         psn = phrase.indexOf(goal.toLowerCase(), psn + 1);

}

return -1;
   }

/**
    * Search for one word in phrase.  The search is not case sensitive.
    * This method will check that the given goal is not a substring of a longer string
    * (so, for example, "I know" does not contain "no").  The search begins at the beginning of the string.
    * @param statement the string to search
    * @param goal the string to search for
    * @return the index of the first occurrence of goal in statement or -1 if it's not found
    */
   private int findKeyword(String statement, String goal)
   {
      return findKeyword (statement, goal, 0);
   }

/**
    * Pick a default response to use if nothing else fits.
    * @return a non-committal string
    */
   private String getRandomResponse()
   {
      final int NUMBER_OF_RESPONSES = 4;
      double r = Math.random();
      int whichResponse = (int)(r * NUMBER_OF_RESPONSES);
      String response = "";

if (whichResponse == 0)
      {
         response = "Interesting, tell me more.";
      }
      else if (whichResponse == 1)
      {
         response = "Hmmm.";
      }
      else if (whichResponse == 2)
      {
         response = "Do you really think so?";
      }
      else if (whichResponse == 3)
      {
         response = "You don't say.";
      }

return response;
   }

public static void main(String[] args)
       {
             Magpie4 maggie = new Magpie4();
             String statement = "I want to build a robot.";
             System.out.println("Statement: " + statement);
             System.out.println("Response: " + maggie.getResponse(statement));
       }

}

You can also step through the code here. It may take a minute or two to load. Click the forward button to execute the next statement (the one with the red arrow).

6.9.1. Exercises:¶

Look at the code. See how it handles “I want to” and you/me statements.

Alter the code:

Have it respond to “I want something” statements with “Would you really be happy if you had something?” In doing this, you need to be careful about where you place the check. Be sure you understand why. For example:
- Statement: I want fried chicken.
- Response: Would you really be happy if you had fried chicken?
Have it respond to statements of the form “I something you” with the restructuring “Why do yo something me?” For example:
- Statement: I like you.
- Response: Why do you like me?

Find an example of when this structure does not work well. How can you improve it?

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