question: private void printData ( Problem problem , boolean reduced , Population population , PrintWriter writer ) { int numberOfVariables = problem . getNumberOfVariables ( ) ; int numberOfObjectives = problem . getNumberOfObjectives ( ) ; if ( reduced ) { numberOfVariables = 0 ; } for ( Solution solution : population ) { for ( int i = 0 ; i < numberOfVariables ; i ++ ) { if ( i > 0 ) { writer . print ( "," ) ; } if ( solution . getVariable ( i ) instanceof RealVariable ) { writer . print ( EncodingUtils . getReal ( solution . getVariable ( i ) ) ) ; } else { writer . print ( "?" ) ; } } for ( int i = 0 ; i < numberOfObjectives ; i ++ ) { if ( ( i > 0 ) || ( numberOfVariables > 0 ) ) { writer . print ( "," ) ; } writer . print ( solution . getObjective ( i ) ) ; } writer . println ( ) ; } }
target:  Prints the given population as the ARFF data section.