*/
public static Instances fromNominalToString(Instances dataset, Object ...columns ){
Instances translated_dataset = dataset;
NominalToString translator = new NominalToString(); // new instance of filter
String col = "";
for(Object c:columns)
col += c.toString()+",";
String[] options = new String[2];
options[0] = "-C"; // "range"
options[1] = col;
try{
translator.setOptions(options); // set options
translator.setInputFormat(translated_dataset); // inform filter about dataset **AFTER** setting options
translated_dataset = Filter.useFilter(translated_dataset, translator); // apply filter
}catch(Exception e){
System.out.println("Exception in filtering the dataset:");
e.printStackTrace();