/**
   * Calculates the p-value of null Hypothesis
   *
   * @param flatDataCollection
   * @param median
   * @return
   * @throws IllegalArgumentException
   */
  public static double getPvalue(FlatDataCollection flatDataCollection, double median)
      throws IllegalArgumentException {
    int n = 0;
    AssociativeArray Di = new AssociativeArray();
    Iterator<Double> it = flatDataCollection.iteratorDouble();
    while (it.hasNext()) {
      double delta = it.next() - median;

      if (delta == 0.0) {
        continue; // don't count it at all
      }

      String key = "+";
      if (delta < 0) {
        key = "-";
      }
      Di.put(key + String.valueOf(n), Math.abs(delta));
      ++n;
    }
    if (n <= 0) {
      throw new IllegalArgumentException();
    }

    // converts the values of the table with its Ranks
    Di.toFlatDataList();
    Ranks.getRanksFromValues(Di);
    double W = 0.0;
    for (Map.Entry<Object, Object> entry : Di.entrySet()) {
      String key = entry.getKey().toString();
      Double rank = TypeInference.toDouble(entry.getValue());

      if (key.charAt(0) == '+') {
        W += rank;
      }
    }

    double pvalue = scoreToPvalue(W, n);

    return pvalue;
  }
Exemplo n.º 2
0
  /**
   * Calculates the score of Chisquare test.
   *
   * @param dataTable
   * @return
   * @throws IllegalArgumentException
   */
  public static AssociativeArray getScore(DataTable2D dataTable) throws IllegalArgumentException {
    if (dataTable.isValid() == false) {
      throw new IllegalArgumentException();
    }
    // Estimate marginal scores and sum
    Map<Object, Double> XdotJ = new HashMap<>();
    Map<Object, Double> XIdot = new HashMap<>();
    double Xdotdot = 0.0;

    for (Map.Entry<Object, AssociativeArray> entry1 : dataTable.entrySet()) {
      Object i = entry1.getKey();
      AssociativeArray row = entry1.getValue();

      for (Map.Entry<Object, Object> entry2 : row.entrySet()) {
        Object j = entry2.getKey();
        Object value = entry2.getValue();

        double v = Dataset.toDouble(value);

        // Summing the columns
        if (XdotJ.containsKey(j) == false) {
          XdotJ.put(j, v);
        } else {
          XdotJ.put(j, XdotJ.get(j) + v);
        }

        // Summing the rows
        if (XIdot.containsKey(i) == false) {
          XIdot.put(i, v);
        } else {
          XIdot.put(i, XIdot.get(i) + v);
        }

        Xdotdot += v;
      }
    }

    int k = XdotJ.size();
    int n = XIdot.size();

    // Calculating Chisquare score
    double ChisquareScore = 0.0;
    if (k == 2
        && n
            == 2) { // if 2x2 then perform the Yates correction. Make this check outside the loops
                    // to make it faster
      for (Map.Entry<Object, AssociativeArray> entry1 : dataTable.entrySet()) {
        Object i = entry1.getKey();
        AssociativeArray row = entry1.getValue();

        for (Map.Entry<Object, Object> entry2 : row.entrySet()) {
          Object j = entry2.getKey();
          Object value = entry2.getValue();

          double v = Dataset.toDouble(value);

          // expected value under null hypothesis
          double eij = XIdot.get(i) * XdotJ.get(j) / Xdotdot;
          if (eij == 0) {
            continue;
          }
          ChisquareScore += Math.pow((Math.abs(v - eij) - 0.5), 2) / eij;
        }
      }
    } else {
      for (Map.Entry<Object, AssociativeArray> entry1 : dataTable.entrySet()) {
        Object i = entry1.getKey();
        AssociativeArray row = entry1.getValue();

        for (Map.Entry<Object, Object> entry2 : row.entrySet()) {
          Object j = entry2.getKey();
          Object value = entry2.getValue();

          double v = Dataset.toDouble(value);

          // expected value under null hypothesis
          double eij = XIdot.get(i) * XdotJ.get(j) / Xdotdot;

          ChisquareScore += Math.pow((v - eij), 2) / eij;
        }
      }
    }
    XdotJ = null;
    XIdot = null;

    AssociativeArray result = new AssociativeArray();
    result.put("k", k);
    result.put("n", n);
    result.put("score", ChisquareScore);

    return result;
  }