public static boolean contextIsCompatible()

in samoa-api/src/main/java/org/apache/samoa/moa/clusterers/AbstractClusterer.java [214:260]

• 39 lines of code
• 11 McCabe index (conditional complexity)

  public static boolean contextIsCompatible(InstancesHeader originalContext,
      InstancesHeader newContext) {
    // rule 1: num classes can increase but never decrease
    // rule 2: num attributes can increase but never decrease
    // rule 3: num nominal attribute values can increase but never decrease
    // rule 4: attribute types must stay in the same order (although class
    // can
    // move; is always skipped over)
    // attribute names are free to change, but should always still represent
    // the original attributes
    if (newContext.numClasses() < originalContext.numClasses()) {
      return false; // rule 1
    }
    if (newContext.numAttributes() < originalContext.numAttributes()) {
      return false; // rule 2
    }
    int oPos = 0;
    int nPos = 0;
    while (oPos < originalContext.numAttributes()) {
      if (oPos == originalContext.classIndex()) {
        oPos++;
        if (!(oPos < originalContext.numAttributes())) {
          break;
        }
      }
      if (nPos == newContext.classIndex()) {
        nPos++;
      }
      if (originalContext.attribute(oPos).isNominal()) {
        if (!newContext.attribute(nPos).isNominal()) {
          return false; // rule 4
        }
        if (newContext.attribute(nPos).numValues() < originalContext
            .attribute(oPos).numValues()) {
          return false; // rule 3
        }
      } else {
        assert (originalContext.attribute(oPos).isNumeric());
        if (!newContext.attribute(nPos).isNumeric()) {
          return false; // rule 4
        }
      }
      oPos++;
      nPos++;
    }
    return true; // all checks clear
  }