docs: public void removeZero() {
  		boolean freeze = false;
  		if (feature.isStopIncrement()) {
  			feature.setStopIncrement(false);
  			freeze = true;
  		}
  		TIntObjectHashMap<String> index = (TIntObjectHashMap<String>) feature.toInverseIndexMap();
  		
  		System.out.println("原字典大小"+index.size());
  		System.out.println("原字典大小"+feature.size());
  		StringFeatureAlphabet newfeat = new StringFeatureAlphabet();
  		cl.factory.setDefaultFeatureAlphabet(newfeat);
  		for(int i=0;i<weights.length;i++){
  				TIntFloatIterator itt = weights[i].data.iterator();
  				HashSparseVector ww = new HashSparseVector();
  				while(itt.hasNext()){
  					itt.advance();
  					float v = itt.value();
  					if(Math.abs(v)<1e-3f)
  						continue;
  					String fea = index.get(itt.key());
  					int newidx = newfeat.lookupIndex(fea);
  					ww.put(newidx, v);				
  			}
  			weights[i] = ww;	
  		}
  		
  		newfeat.setStopIncrement(freeze);
  		System.out.println("新字典大小"+newfeat.size());		
  		System.out.println("新字典大小"+feature.size());		
  		index.clear();		
  	}