code: /**
   * boilerpipe
   *
   * Copyright (c) 2009, 2014 Christian Kohlschütter
   *
   * The author licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.kohlschutter.boilerpipe.estimators;
  
  import com.kohlschutter.boilerpipe.BoilerpipeExtractor;
  import com.kohlschutter.boilerpipe.document.TextDocumentStatistics;
  import com.kohlschutter.boilerpipe.extractors.ArticleExtractor;
  import com.kohlschutter.boilerpipe.extractors.DefaultExtractor;
  
  /**
   * Estimates the "goodness" of a {@link BoilerpipeExtractor} on a given document.
   */
  public final class SimpleEstimator {
  
    /**
     * Returns the singleton instance of {@link SimpleEstimator}
     */
    public static final SimpleEstimator INSTANCE = new SimpleEstimator();
  
    private SimpleEstimator() {
    }
  
    /**
     * Given the statistics of the document before and after applying the {@link BoilerpipeExtractor},
     * can we regard the extraction quality (too) low?
     * 
     * Works well with {@link DefaultExtractor}, {@link ArticleExtractor} and others.
     * 
     * @param dsBefore
     * @param dsAfter
     * @return true if low quality is to be expected.
     */
    public boolean isLowQuality(final TextDocumentStatistics dsBefore,
        final TextDocumentStatistics dsAfter) {
      if (dsBefore.getNumWords() < 90 || dsAfter.getNumWords() < 70) {
        return true;
      }
  
      if (dsAfter.avgNumWords() < 25) {
        return true;
      }
  
      return false;
    }
  
  }
  