example15_get_input.zubr

An optimizer created by zubr communicates with the outer world via two methods:

• getInput
• execute

What is an optimizer? From our point of view the optimizer runs in a loop:

    while (loopIsRunning):
        getInput(...)
        ....
        execute(...)


In this example we tell zubr that the method getInput will be provided by us. The other one, "execute" will be a default one. We will provide an implementation of getInput which will enable the user to set one input variable at one of two values it may have.

// This is an example zubr specification.

package optimizer;

%option class MyOptimizer    // here we modify the target class name, it is optional
%option getinput own    // with this option we tell zubr we will provide our own implementation of the method getInput

// We can import Java packages here.
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import java.awt.Dimension;

In the middle section we provide the Perkun code declaring one input variable, alpha, which may have one of the two values - FALSE or TRUE.

// here we put the Perkun code (values and variables)

values
{
    value FALSE, TRUE;
}

variables
{
    input variable alpha:{FALSE, TRUE};   
}

The method getInput looks as follows:
// this is the implementation of the method we promised to provide:
protected void getInput(Map<Variable, Value> m) {

    Object[] possibilities = {"FALSE", "TRUE"};
   
    String n = (String)JOptionPane.showInputDialog(frame, "Alpha=?", "Continue?", JOptionPane.PLAIN_MESSAGE,
         null, possibilities, "FALSE");
      if (n == null) {
        loopIsRunning = false; // here we tell the optimizer we want to break the loop
      }
      else
      if (n == "FALSE") {
         m.put(mapNameToVariable.get("alpha"), Value.FALSE);
      }
      else
      if (n == "TRUE") {
         m.put(mapNameToVariable.get("alpha"), Value.TRUE);
     
}
It is filling the map Map<Variable,Value> named "m" with values for all input variables, depending on the decision made by the user. We are free to use the map Map<String,Variable> named "mapNameToVariable" to access the variable "alpha". The Value is an enum created by zubr.

In more complex cases we will possibly have more input variables, then we will provide a different dialog.

When we run this example with zubr we will obtain a Java code:

zubr example15_get_input.zubr > MyOptimizer.java

After compiling and running it a dialog will be shown to set the variable "alpha" either with FALSE or TRUE. After you enter the alpha value twice (and press OK) an error will occur. Moreover - this error will not be reported, and we would like to have a Swing dialog shown when it happens. How to achieve this? We must provide an important error handling method, which will be discussed in the next example. The default version of this method does nothing, and the error should be handled otherwise.

example14_my_optimizer.zubr

Next example - example14_my_optimizer.zubr. In the declaration section we have the following code:


// This is an example zubr specification.

package optimizer;

%option class MyOptimizer    // here we modify the target class name, it is optional

// We can import Java packages here.
import javax.swing.JFrame;
import java.awt.Dimension;

The instruction %option class MyOptimizer is not a Java code, it is a zubr option. It tells zubr we want to change the default target class name. Nothing complicated. We must take it into account and modify the class OptimizerThread accordingly:


protected static class OptimizerThread extends Thread {
    private MyOptimizer optimizer;

    public void run() {
        optimizer = new MyOptimizer();
        optimizer.loop(1);
      }
}

Now it creates MyOptimizer rather than Optimizer. Also note that we added in the declaration section "package optimizer;" - this means that we have to place the result Java code in a package "optimizer" (you have to create the package). As usual we can execute this example with zubr:

zubr example14_my_optimizer.zubr > MyOptimizer.zubr

The result code should be compiled with a java compiler and executed. But it still only instantiates an optimizer and runs the loop without any means to communicate with the outer world. How to make the communication? Be patient, this will be covered in next examples.

For the Windows users - I have created an installer: http://www.pawelbiernacki.net/perkun.msi.

Download zubr from https://sourceforge.net/projects/perkun/.

example13_with_optimizer_thread.zubr

Next example from the "examples" folder of the perkun package. The definition section contains the code:

// the OptimizerThread class creates an instance of the Optimizer class (created by zubr)
// and runs the loop.

protected static class OptimizerThread extends Thread {
    private Optimizer optimizer;

    public void run() {
        optimizer = new Optimizer();
        optimizer.loop(1);
      }
}

public static void main(String[] args) {
    frame = new JFrame();
    frame.setTitle("Optimizer");
    frame.setSize(new Dimension(800, 600));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
   
    OptimizerThread t = new OptimizerThread();
   
    t.start();
}
In short - we create a thread that creates an optimizer and calls its method "loop". In the loop the optimizer runs as long as the predefined boolean variable isLoopRunning equals true. This variable is defined by zubr, you do not need to define it, but you can access it in the Optimizer.

Try to execute the example with zubr:

zubr example13_with_optimizer_thread.zubr > Optimizer.java

That is all - it will create a Java class with the code shown above included. But the optimizer (although running) does not communicate with the outer world. It is no good for us. We need to define some optimizer's methods to do it. We will do it in next examples.

Download zubr from https://sourceforge.net/projects/perkun/.

example12_with_frame.zubr

This is another zubr example from the Perkun's "examples" folder. It merely demonstrates that we can open a Swing frame when running the program. There are still no Perkun values or variables. Also the optimizer class is not instantiated yet.


// This is an example zubr specification.

// We can import Java packages here.
import javax.swing.JFrame;
import java.awt.Dimension;

%%

// here we put the Perkun code (values and variables)

values {}
variables {}

%%

// here we put Java code to be included in the result class

private static JFrame frame;

public static void main(String[] args) {
    frame = new JFrame();
    frame.setTitle("Optimizer");
    frame.setSize(new Dimension(800, 600));
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);   
}

Try to process the example file with zubr:

zubr example12_with_frame.zubr > Optimizer.java

Then compile Optimizer.java with your Java compiler and run it. It will open a frame. When you close the frame the program terminates. Not a big deal. The example just shows how to include Java into your zubr specification.

Download zubr from https://sourceforge.net/projects/perkun/.

example11_simple.zubr

I thought I would present the subsequent zubr examples from the "examples" folder in the package perkun. Let us begin with example11_simple.zubr:


// This is an example zubr specification.

%%

// here we put the Perkun code (values and variables)

values {}
variables {}

%%

// here we put Java code to be included in the result class

In the above example we have a legal zubr specification. We begin with a declaration section where we can place for example Java imports. Then we have a separator %% and a Perkun section follows, with two subsections - values and variables. Then we have another separator %% and definition section follows, where we can place the Java code to be included within the result class.

Let us run:
zubr example11_simple.zubr > Optimizer.java

This will produce a Java code. The code will contain an Optimizer class which needs to be instantiated. Then we can run the instance's "loop" method. 

This simple example does not contain any Perkun variables, its purpose is just to demonstrate the zubr concept. Next examples will generate Java code based on the Java Swing package.

Download the zubr tool with the package: https://sourceforge.net/projects/perkun/.

zubr - an optimizer generator tool producing Java code in Perkun 0.1.6

I made some improvements for zubr and wrote several examples. They can be found in the "examples" folder. Zubr comes as a companion tool in the Perkun package:

https://sourceforge.net/projects/perkun/

The examples are:

• example11_simple.zubr
• example12_with_frame.zubr 
• example13_with_optimizer_thread.zubr
• example14_my_optimizer.zubr
• example15_get_input.zubr
• example16_on_error_in_populate_belief_for_consequence.zubr
• example17_get_model_probability.zubr
• example18_simple_automaton.zubr
• example19_get_payoff.zubr
• example20_hidden_variables.zubr
• example21_set_apriori_belief.zubr

 They are ordered in the increasing complexity. I recommend running the Java code produced by them. In order to try out an example (say the last one) run:

zubr example21_set_apriori_belief.zubr > MyOptimizer.java

Then create a Java application project (for example in NetBeans), put the file MyOptimizer.java in the source folder (package "optimizer") and enjoy a simple optimizer generated by zubr!

I decided that only the Perkun values and variables are passed in the zubr specification - the apriori probabilities and the model probabilities are passed in pure Java (there is no special zubr syntax for them). It is better like that.

Perkun 0.1.5 released!

Perkun 0.1.5 has been released! It contains the "zubr" tool. In the folder examples there is an example zubr specification (example10_java.zubr). If you process the file with zubr you will get a Java code containing class MyOptimizer.

There is no manual for zubr yet, I will write it.