ECJ Quick Help FAQs

• Q: Where/how can I perform pre-execution actions such as setting up my training/testing sets, printing my params to the console, etc?
  A) Within your problem implementation file, implement your pre-execution actions in a method with the following signature:
  public void setup(final EvolutionState state, final Parameter base)
• Q: Where/how can I evaluate an individuals fitness using my designated fitness function?
  A) Within your problem implementation file, implement your fitness calculation algorithm in a method with the following signature:
  public void evaluate(final EvolutionState state, final Individual ind, final int subpopulation, final int threadnum)
  *Note that ind references the current individual being evaluated.
• Q: Where/how can I perform post-execution actions such as printing out the performance of the best individual on the testing set, printing out a confusion matrix, etc?
  A) Within your problem implementation file, implement your post-execution actions in a method with the following signature:
  public void describe(EvolutionState state, Individual bestIndividual, int subpopulation, int threadnum, int log)
  *Note that bestIndividual allows one to access the overall best performing individual of the entire run.
• Q: Where/how can I print statistics after each generation such as the population average fitness, etc?
  A) Within the file ecj/ec/simple/SimpleStatistics.java, you can calculate and print statistics after each generation in the postEvaluationStatistics method.
• Q: Where/how can I print statistics after the final generation such as the average population fitness over all generations, etc?
  A) Within the file ecj/ec/simple/SimpleStatistics.java, you can calculate and print final statistics in the finalStatistics method.
  Tip: Use the postInitializationStatistics method to initialize any needed data structures.
• Q: How can I retrieve a parameter value from my .param file into my problem implementation file?
  A) state.parameters.getInt(base.push(<name of parameter here>)
  *Note that if your parameter was of type double you would use getDouble, etc...
• Q: How can I print a message to the console?
  A) state.output.message(String message)
• Q: How can I throw a fatal error to stop program execution?
  A) state.output.fatal(String message,Parameter paramCausingError)
• Q: How can I output a warning to the console?
  A) state.output.warning(String message,Parameter paramCausingWarning)
• Q: How can I output a message to the output log?
  A) state.output.println(String message,int log)
• Q: Where do I modify the elitism parameter?
  A) ecj/ec/simple/simple.params
• Q: Where do I modify parameters such as crossover rate, mutation rate, max tree depth, tournament selection size, etc?
  A) ecj/ec/simple/koza.params, assuming you are using koza GP.
• Q: Where do I create my own runtime parameters and modify the function set to use?
  A) Params files are created in a separate directory from the problem: resources/ec/app/myProblem/myProblem.params .
  This is because maven uses the resources folder for building.
• Q: Can I modify parameters without modifying the defaults?
  A) Yes, you can edit them in your own .params file. This will leave the defaults alone (e.g. /ecj/ec/simple/simple.params can be left untouched).
• Q: Do I need to recompile after changing a .params file?
  A) If you want to make changes to the .params file without recompiling, you have to go to:
  target/classes/ec/app/myProblem/myProblem.params
  which is where the class files are after compiling.
  Any changes in the target/classes don't change the resources files so if you changed the target/classes .params and then recompile, it will use the .params file in the resources directory.
• Q: Can I modify parameters on a command line, say, while working in a Linux shell?
  A) Yes. Add this to your command line: -p param1 param2...
  So for example, adding this will add a seed and new max generation to your run: -p seed.0=1, generation=50

Back to COSC 5P71 home