Welcome to the Java Programming Forums


The professional, friendly Java community. 21,500 members and growing!


The Java Programming Forums are a community of Java programmers from all around the World. Our members have a wide range of skills and they all have one thing in common: A passion to learn and code Java. We invite beginner Java programmers right through to Java professionals to post here and share your knowledge. Become a part of the community, help others, expand your knowledge of Java and enjoy talking with like minded people. Registration is quick and best of all free. We look forward to meeting you.


>> REGISTER NOW TO START POSTING


Members have full access to the forums. Advertisements are removed for registered users.

Results 1 to 3 of 3

Thread: MarkovBot

  1. #1
    Junior Member
    Join Date
    Sep 2013
    Posts
    16
    Thanks
    1
    Thanked 0 Times in 0 Posts

    Default MarkovBot

    I need a little help in understanding how to run this Markov Chain program (It's one of those Mark V Shaney type programs). The code itself is from The Practice of Programming by Keringhan and Pike. It's on Page 81 if anyone is particularly interested in cross-referencing. The way I understood their instructions, I should be able to produce the formatted version of the processed file by typing java Markov <goo.txt |fmt. However, when I do this the text remains unchanged. If I simply type java Markov <goo.txt without the extension it will jumble the text according to the Markov algorithm, but print it on a one word one line basis. It's probably a very simple thing I'm missing, but my understanding of how to run java programs from the terminal is still very basic. If anyone wants me to give examples of the file content and the output for different commands I will provide it, but I don't want this post to get too long, and I think it's more important to show the sample code below.


    import java.io.IOException;
    import java.io.InputStream;
    import java.io.StreamTokenizer;
    import java.util.Hashtable;
    import java.util.Random;
    import java.util.Vector;
     
     
    public class Chain {
    	static final int NPREF = 2; //size of prefix
    	static final String NONWORD = "\n";
    		//"word" that can't appear
    	Hashtable statetab = new Hashtable();
    		//key = Prefix, value = suffix Vector
    	Prefix prefix = new Prefix(NPREF,NONWORD);
    		//initial prefix
    	Random rand = new Random();
     
    	//Chain build: build State table from input stream
    	void build (InputStream in )throws IOException{
    		@SuppressWarnings("deprecation")
    		StreamTokenizer st = new StreamTokenizer(in);
     
    		st.resetSyntax();  //remove default rules
    		st.wordChars(0,Character.MAX_VALUE); //turn on all chars
    		st.whitespaceChars(0, ' ');
    		while(st.nextToken()!= st.TT_EOF)
    			add(st.sval);
    		add(NONWORD);
    	}
     
    	//Chain add: add word to suffix list, update prefix
    	void add(String word){
    		Vector suf = (Vector) statetab.get(prefix);
    		if(suf== null){
    			suf = new Vector();
    			statetab.put(new Prefix(prefix), suf);
    		}
    		suf.addElement(word);
    		prefix.pref.removeElementAt(0);
    		prefix.pref.addElement(word);
     
    	}
     
    	//Chain generate: generate output words
    	void generate(int nwords){
    		prefix = new Prefix(NPREF,NONWORD);
    		for(int i =0;i<nwords;i++){
    			Vector s = (Vector) statetab.get(prefix);
    			int r = Math.abs(rand.nextInt())%s.size();String suf = (String) s.elementAt(r);
    			if(suf.equals(NONWORD) )
    				break;
    			System.out.println(suf);
    			prefix.pref.removeElementAt(0);
    			prefix.pref.addElement(suf);
    		}
    	}
     
    }

    import java.util.Vector;
     
     
    public class Prefix {
     
    	static final int MULTIPLIER = 31;
     
    	public Vector pref;
     
    	//Prefix constructor: duplicate existing prefix
    	Prefix (Prefix p){
    		pref = (Vector) p.pref.clone();
    	}
     
    	//Prefix constructor: n copies of str
    	Prefix (int n, String str){
    		pref = new Vector();
    		for(int i = 0;i<n; i++)
    			pref.addElement(str);
    	}
     
    	//Prefix hashcode: generate hash from all prefi words
    	public int hashCode(){
    		int h = 0;
    		for(int i =0; i<pref.size();i++)
    			h = MULTIPLIER * h + pref.elementAt(i).hashCode();
    			return h;
    	}
     
    	//Prefix equals: compare two prefixes for equal words
    	public boolean equals(Object o){
    		Prefix p = (Prefix)o;
    		for(int i =0;i<pref.size();i++)
    			if (!pref.elementAt(i).equals(p.pref.elementAt(i)))
    				return false;
     
    		return true;
    	}
     
    }

    import java.io.IOException;
     
     
    public class Markov {
    	static final int MAXGEN = 1000;//maximum words generated
     
    	public static void main (String [] args) throws IOException
    	{
    		Chain chain = new Chain();
    		int nwords = MAXGEN;
     
    		chain.build(System.in);
    		chain.generate(nwords);
    	}
     
    }


    --- Update ---

    Actually, now that I've tried it again, both methods seem to be producing the words in the original order. Maybe something is wrong with the way I copied down the program?

  2. #2
    Super Moderator
    Join Date
    Jun 2013
    Location
    So. Maryland, USA
    Posts
    5,520
    My Mood
    Mellow
    Thanks
    215
    Thanked 698 Times in 680 Posts

    Default Re: MarkovBot

    Maybe something is wrong with the way I copied down the program?
    Check that and let us know.

  3. #3
    Junior Member
    Join Date
    Sep 2013
    Posts
    16
    Thanks
    1
    Thanked 0 Times in 0 Posts

    Default Re: MarkovBot

    My bad. There was absolutely nothing wrong with this code. I'm not sure what was causing the problem in the first place though. I probably just didn't run it correctly.