docs: @Override
  	public int generateAt(Instance instance, IFeatureAlphabet features, int pos,
  			int... numLabels) {
  		String[][] data = ( String[][]) instance.getData();
  		
  		int len = data[0][pos].length();
  		
  		StringBuilder sb = new StringBuilder();
  
  		sb.append(id);
  		sb.append(':');
  		int indx = position;
  		if(indx<0)
  			indx = len+indx;
  		if(indx<0)
  			indx=0;
  		int endIdx = indx+plen;
  		if(endIdx>len)
  			endIdx = len;
  		String str = data[0][pos].substring(indx,endIdx); //这里数据行列和模板中行列相反				
  		sb.append(str);	
  //		System.out.println(sb.toString());
  		int index = features.lookupIndex(sb.toString(), numLabels[0]);
  		return index;
  	}