Extending genetic operators

 

Extending genetic operators works more or less the same way than views: it is a matter of creating new letter classes, and changing some stuff in the envelope class. We will create a new operator, shift, which adds or substract one from one gene, substracting or adding one to the next at the same time.

• The operator name, for instance, SHIFT should be added to the enum in the genOp class header, that is, line 30 of the genop.hpp file.
• A new genOp constructor for the new class will be needed. If so, add it to the genOp header and declare it; if parameters are more or less the same than already defined operators, use one of the existing constructors. Not in this case, since shift only needs the gene size, which use the second constructor. This means that this constructor must be modified anyways. Go to the genop.cc file, around line 77, and add something like this:

          case SHIFT:
              op = new shiftOp( _lenBits );
              arity = FALSE;
              break;

  which creates the letter object for the new operator class, and assigns it FALSE arity, that is, arity one. Binary operators would have TRUE arity.
• Go to the genopimp.hpp header, to create the class interface, and copy whatever other class interface suits you the best, this means that you have already operator () with arity one and two defined, constructor, but not copy constructor. It does not make much sense to copy genetic operators. In this case, you can directly copy creepOp declaration and change names.
• Write implementation of the genetic operator, and put it genopimp.cc or your own file. In this implementation, try to use the functions in genop.cc, remember that the letters cannot access chroms directly, only the envelope. Take a look at the implementation of the other genetic operators, so that you have an idea of how things are done.