code: public String selectBasicTransform() {
      if( _ignored )                 return "ignored";
      if( _v.isBinary() )            return "none";
      if( _v.isTime() || _isDate )   return "time";  // actually we have a time/date column, so apply some time transforms
      if( _v.max() - _v.min() > 1e4) return "log";   // take a log if spans more than 2 orders
      if( _v.isNumeric() && !_v.isInt() ) return "recip"; // try the reciprocal!
      return "none";                                 // no transform if not interesting
    }
docs: TODO: enum, please!