} else if (cls.equals("fraction")) {
float fraction = createFloat(commandLine, "fraction");
filter = new FractionSelector(fraction);
} else if (cls.equals("probability")) {
float probability = createFloat(commandLine, "probability");
filter = new ProbabilitySelector(probability);
} else if (cls.equals("intersection") || cls.equals("difference")) {
String alignmentString = commandLine.getOptionValue("alignment");
if (alignmentString == null) {
throw new MissingParameterException("alignment");
}