001/** 
002 * Copyright (c) 2007-2012, Regents of the University of Colorado 
003 * All rights reserved.
004 * 
005 * Redistribution and use in source and binary forms, with or without
006 * modification, are permitted provided that the following conditions are met:
007 * 
008 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 
009 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 
010 * Neither the name of the University of Colorado at Boulder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. 
011 * 
012 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
013 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
014 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
015 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
016 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
017 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
018 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
019 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
020 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
021 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
022 * POSSIBILITY OF SUCH DAMAGE. 
023 */
024package org.cleartk.ml.feature.function;
025
026import java.util.Collections;
027import java.util.List;
028import java.util.regex.Pattern;
029
030import org.cleartk.ml.Feature;
031import org.cleartk.ml.feature.util.NumericTypeUtil;
032
033/**
034 * <br>
035 * Copyright (c) 2007-2012, Regents of the University of Colorado <br>
036 * All rights reserved.
037 * 
038 * 
039 * @author Philip Ogren
040 * 
041 */
042
043public class NumericTypeFeatureFunction implements FeatureFunction {
044
045  public static final String DEFAULT_NAME = "NumericType";
046
047  public enum NumericType {
048    DIGITS, // all characters are digits.
049    YEAR_DIGITS, // characters look like a year - i.e. string is 4 digits starting with 1, 20 or 21
050    ALPHANUMERIC, // All characters are either letters or digits
051    SOME_DIGITS, // Contains some digits and some non-letters - but can still contain letters
052    ROMAN_NUMERAL
053    // matches a regular expression for Roman numerals.
054  }
055
056  static Pattern yearDigitsPattern = Pattern.compile("(?:1[0-9]{3,3})|(?:2[0|1][0-9]{2,2})");
057
058  static Pattern alphanumericPattern = Pattern.compile("[a-zA-Z0-9-]+");
059
060  static Pattern someLetters = Pattern.compile("[a-zA-Z]");
061
062  static Pattern romanNumeralPattern = Pattern.compile("^M?M?M?(CM|CD|D?C?C?C?)(XC|XL|L?X?X?X?)(IX|IV|V?I?I?I?)$");
063
064  /**
065   * If the value of the feature is a StringValue and is determined to be one of DIGITS,
066   * YEAR_DIGITS, ALPHANUMERIC, SOME_DIGITS, or ROMAN_NUMERAL, then a feature containing one of
067   * those five values is returned. If the value of the feature cannot be characterized by one of
068   * these five values, then an empty list is returned (e.g. the value is an empty string, contains
069   * only white space, or contains only letters, etc.)
070   * 
071   * <p>
072   * This method draws heavily from NumericTypeTagger.py written by Steven Bethard. That code
073   * credits <a href="http://diveintopython.org/unit_testing/stage_5.html">Dive Into Python</a> for
074   * the regular expression for matching roman numerals.
075   * 
076   * @return a feature that has a value that is one of DIGITS, YEAR_DIGITS, ALPHANUMERIC,
077   *         SOME_DIGITS, or ROMAN_NUMERAL. Otherwise an empty list is returned.
078   */
079
080  @Override
081  public List<Feature> apply(Feature feature) {
082    String featureName = Feature.createName(DEFAULT_NAME, feature.getName());
083    Object featureValue = feature.getValue();
084    if (featureValue == null)
085      return Collections.emptyList();
086    else if (featureValue instanceof String) {
087      String value = featureValue.toString();
088      if (value == null || value.length() == 0)
089        return Collections.emptyList();
090
091      if (NumericTypeUtil.isDigits(value)) {
092        if (yearDigitsPattern.matcher(value).matches()) {
093          return Collections.singletonList(new Feature(
094              featureName,
095              NumericType.YEAR_DIGITS.toString()));
096        } else
097          return Collections.singletonList(new Feature(featureName, NumericType.DIGITS.toString()));
098      } else if (NumericTypeUtil.containsDigits(value)) {
099        if (alphanumericPattern.matcher(value).matches() && someLetters.matcher(value).find()) {
100          return Collections.singletonList(new Feature(
101              featureName,
102              NumericType.ALPHANUMERIC.toString()));
103        } else
104          return Collections.singletonList(new Feature(
105              featureName,
106              NumericType.SOME_DIGITS.toString()));
107      } else if (romanNumeralPattern.matcher(value).matches()) {
108        return Collections.singletonList(new Feature(
109            featureName,
110            NumericType.ROMAN_NUMERAL.toString()));
111      }
112    }
113    return Collections.emptyList();
114  }
115}