Hi, I need to produce an initial population. I have taken a look at earlier posts on generating initial population and the example in the manual. I've tried using the Coder like in one of the posts. I have added the genome count and have gotten it to run. However, I got an error as such. ONCE-ONLY WARNING: On reading subpopulation from text stream, some of the preexisting subpopulation's slots were null. Had to use newIndividual() instead of readIndividual(). If you're starting an evolutionary run by reading an existing population from a file, this is expected -- ignore this message. ONCE-ONLY WARNING: On reading subpopulation from text stream, some individual indexes in the subpopulation did not match. The first was individual 1, which is listed in the file as 2 Exception in thread "Thread-8" java.lang.NullPointerException at MyOptimiser.MyOptimiser.evaluate(MyOptimiser.java:81) at ec.simple.SimpleEvaluator.evalPopChunk(SimpleEvaluator.java:146) at ec.simple.SimpleEvaluatorThread.run(SimpleEvaluator.java:177) at java.lang.Thread.run(Unknown Source) Generation 1 My pop.in file looks like this. Number of Individuals: i2| Individual Number: i0| Evaluated: F Fitness: f0|0.0| i4|f1056964608|0.5|f1056964608|0.5|f1056964608|0.5|f1056964608|0. 5| Individual Number: i1| Evaluated: F Fitness: f0|0.0| i4|f1065353216|1.0|f1065353216|1.0|f1065353216|1.0|f1065353216|1. 0| Individual Number: i2| Evaluated: F Fitness: f0|0.0| i4|f1048576000|0.25|f1048576000|0.25|f1048576000|0.25|f104857600 0|0.25| Individual Number: i3| Evaluated: F Fitness: f0|0.0| i4|f1061158912|0.75|f1061158912|0.75|f1061158912|0.75|f106115891 2|0.75| Oddly, when I don't add the third individual I will get a preamble error where Indiviudal Number: is expected. There was a comment about using printIndividual(..). How can I use this method? The method requires EvolutionState, ParameterDatabase etc. I have a set of individuals that I want to format external from the ECJ framework itself. Is there a way that I can use printIndividual(..) without having to construct the whole framework? thanks.