question: public static String formatNumber ( double value , int numberOfDigits , boolean groupingCharacters ) { if ( Double . isNaN ( value ) ) { return "?" ; } int numberDigits = numberOfDigits ; if ( numberDigits < 0 ) { numberDigits = numberOfFractionDigits ; } NUMBER_FORMAT . setMinimumFractionDigits ( numberDigits ) ; NUMBER_FORMAT . setMaximumFractionDigits ( numberDigits ) ; NUMBER_FORMAT . setGroupingUsed ( groupingCharacters ) ; return NUMBER_FORMAT . format ( value ) ; }
target:  Returns a formatted string of the given number (uses the property rapidminer.gui.fractiondigits.numbers if the given number of digits is smaller than 0 (usually 3)).