Vectors of Vectors or hash-somethings?

[mindwarp]

Hi All,

I have an object called PICSet, which stores info about groups of pictures.
Each PICSet instance has a Vector of Associated Images (strings)
Each PICSet instance also has a Vector of Features (AU's) visible in that group..

I have another class which manipulates a vector of these PICSet objects (so there are Lots of sessions/groups)

Code:

class PICSet{
	public String SUBJECT;
	public String SESSION;
	public Vector ASSOCIATEDIMAGES; // actually contains Strings (filenames)
	public Vector AUsPresent;	// actually contains ints

	public PICSet(String subj, String sess)
	public String toString()
	public void AssociateAU(int AU)
}

class PICSetManager{
	Vector PICSets = new Vector();
}

Given a particular AU feature, I want to find All associated images from the Vector PICSets.

What's the easiest - most efficient - way of doing this?
If there's a better way of doing this (including HashTable/Maps etc) I'd like to know please...

__________
MindWarp

[hardwired]

Code:

import java.util.*;
import java.util.List;

public class PICTest {
    // Make up some AU constants.
    static final int A = 1;
    static final int B = 2;
    static final int C = 3;
    static final int D = 4;

    public static void main(String[] args) {
        PICStoreManager manager = new PICStoreManager();
        // Add some PICStores.
        addStores(manager);

        // Add some image fileNames.
        addImageNames(manager);

        // Add some AU features.
        addFeatures(manager);

        for(PICStore store : manager.picStores)
            System.out.println(store);

        // Collect the image filePaths for the AU feature A.
        List<String> list = manager.getImagesByAU(A);
        for(int j = 0; j < list.size(); j++) {
            System.out.println((String)list.get(j));
        }
    }

    private static void addStores(PICStoreManager manager) {
        // Make up some PICStores to manage.
        String[] subjects = {
            "town hall", "steeple", "clown", "river"
        };
        String[] sessions = {
            "first", "ninth", "third", "sixth"
        };
        List<PICStore> picStores = manager.picStores;
        for(int j = 0; j < subjects.length; j++) {
            picStores.add(new PICStore(subjects[j], sessions[j]));
        }
    }

    private static void addImageNames(PICStoreManager manager) {
        String[][] fileNames = {
            { "entrance.jpg" },
            { "center.png", "top.jpg", "detail.jpg" },
            { "face.gif", "hands.jpg" },
            { "surface.gif", "southBend.png", "bottom.gif", "swirl.jpg" }
        };
        List<PICStore> picStores = manager.picStores;
        for(int j = 0; j < picStores.size(); j++) {
            PICStore store = (PICStore)picStores.get(j);
            for(int k = 0; k < fileNames[j].length; k++) {
                store.addImageName(fileNames[j][k]);
            }
        }
    }

    private static void addFeatures(PICStoreManager manager) {
        int[][] features = {
            { C, A }, { B, D, C }, { A }, { B, A }
        };
        List<PICStore> picStores = manager.picStores;
        for(int j = 0; j < picStores.size(); j++) {
            PICStore store = (PICStore)picStores.get(j);
            for(int k = 0; k < features[j].length; k++) {
                store.AssociateAU(features[j][k]);
            }
        }
    }
}

class PICStoreManager {
    List<PICStore> picStores = new ArrayList<PICStore>();

    public void addPICStore(PICStore store) {
        picStores.add(store);
    }

    public List<String> getImagesByAU(int AU) {
        Integer target = Integer.valueOf(AU);
        List<String> list = new ArrayList<String>();
        for(PICStore store : picStores) {
            if(store.AUsPresent.contains(target)) {
                // Found the target AU feature in this store.
                // Add all the image pathStrings to list.
                list.addAll(store.ASSOCIATEDIMAGES);
            }
        }
        return list;
    }
}

class PICStore {
    public String SUBJECT;
    public String SESSION;
    public List<String>  ASSOCIATEDIMAGES;  // contains Strings (filenames)
    public List<Integer> AUsPresent;	    // contains ints

    public PICStore(String subj, String sess) {
        SUBJECT = subj;
        SESSION = sess;
        ASSOCIATEDIMAGES = new ArrayList<String>();
        AUsPresent = new ArrayList<Integer>();
    }

    public String toString() {
        return getClass().getName() + "[SUBJECT:" + SUBJECT +
                                      " SESSION:" + SESSION + "]";
    }

    public void addImageName(String name) {
        ASSOCIATEDIMAGES.add(name);
    }

    public void AssociateAU(int AU) {
        // What if AUsPresent already contains this AU feature?
        AUsPresent.add(new Integer(AU));
    }
}

[mindwarp]

Hi, thanks for answering

I have some questions on your code:

In PICStoreManager, why did you use " Integer target = Integer.valueOf(AU); "
instead of " int target = Integer.valueOf(AU); " ????? Why are you wrapping the int into an Integer?

In PICStore.AssociateAU(int AU) wrt the comment - I first check that it's not already there..

Also, I did a small experiment:

Code:

import java.util.*;

public class vectortest{
	static class newobj{
		int val;
		int val2;
		public newobj(int v1,int v2){ val = v1; val2 = v2;}
		public String toString(){ 
			return ( "[" + getClass().getName() + ": " + val + ", " + val2 + "]" ); 
		}
	}
	
	
	public static void main(String[] args){

		Vector V1 = new Vector();

		for (int i = 0; i< 6; i++) V1.add(i);
		
		for (int i = 0; i< 5; i++) V1.add((char)('a'+ i));
		
		for (int i = 27; i< 31; i++) V1.add(i);
		
		boolean b = true;
		for (int i = 0; i < 5; i++){
			 V1.add(b);
			 b  = (b ? false: true);
		}
		
		for (int i = 0; i < 5; i++) V1.add(new newobj(i,i+2)); 		
		
		
		for (int j = 0; j<V1.size(); j++){  
			System.out.print("{" + (""+V1.elementAt(j)).toString()+ "}");
		}
		
		System.out.println();
		System.out.println("vector contains a 3: " + V1.contains(3));
		System.out.println("vector contains a 5: " + V1.contains(5));
		System.out.println("vector contains a a: " + V1.contains('a'));
		System.out.println("vector contains a e: " + V1.contains('e'));
		System.out.println("vector contains a 30: " + V1.contains(30));
		System.out.println("vector contains a 31: " + V1.contains(31));
		newobj no = new newobj(1,3);
		System.out.println("vector contains a newobj(1,3):" + V1.contains(no));
		System.out.println();
	
	}
}

output:

Quote:

{0}{1}{2}{3}{4}{5}{a}{b}{c}{d}{e}{27}{28}{29}{30}{ true}{false}{true}{false}{true}{[vectortest$newobj: 0, 2]}{[vectortest$newobj: 1, 3]}{[vectortest$newobj: 2, 4]}{[vectortest$newobj: 3, 5]}{[vectortest$newobj: 4, 6]}
vector contains a 3: true
vector contains a 5: true
vector contains a a: true
vector contains a e: true
vector contains a 30: true
vector contains a 31: false
vector contains a newobj(1,3):false

So, why is it not easier to do the following (looks a lot like your code)?

Code:

	public String getImagesByAU(int AU){ // untested, pls excuse any typos
		
		Vector imgsFound = new Vector();
		
		for (int i = 0; i< PICSets.size(); i++){
			if (((PICSet) (PICSets.elementAt(i))).AUsPresent.contains(AU))
				imgsFound.addAll( (PICSet) (PICSets.elementAt(i).ASSOCIATEDIMAGES)  );
		}
		return imgsFound;	
	}

Changing to Lists will mean significant rewriting of my code, but if the advantage is that much greater then it is an option I'll look at.
Would you like to deliberate?
Also, I was hoping for a solution using a structure that could automatically map them AU features to ASSOCIATEDIMAGES, if at all possible (without writing the structure myself)

[hardwired]

In PICStoreManager, why did you use " Integer target = Integer.valueOf(AU); "
instead of " int target = Integer.valueOf(AU); " ????? Why are you wrapping the int into an Integer?
Collections take Objects and not primitives. The auto–boxing feature in j2se 1.5+ allows us to overlook this.

In PICStore.AssociateAU(int AU) wrt the comment - I first check that it's not already there..
Just another option: whether you want multiple AU feature constants in the collection or not. Depends on what you are doing.

So, why is it not easier to do the following (looks a lot like your code)?
Looks like you have things figured out the way you want them.

Changing to Lists will mean significant rewriting of my code, but if the advantage is that much greater then it is an option I'll look at.
Vectors are fine.