public CompactSketch getResult()

in src/main/java/org/apache/datasketches/tuple/Union.java [153:214]
51 lines of code
13 McCabe index (conditional complexity)

  public CompactSketch<S> getResult(final boolean reset) {
    final CompactSketch<S> result;
    if (empty_) {
      result = qsk_.compact();
    } else if (unionThetaLong_ >= qsk_.thetaLong_ && qsk_.getRetainedEntries() <= qsk_.getNominalEntries()) {
      //unionThetaLong_ >= qsk_.thetaLong_ means we can ignore unionThetaLong_. We don't need to rebuild.
      //qsk_.getRetainedEntries() <= qsk_.getNominalEntries() means we don't need to pull back to k.
      result = qsk_.compact();
    } else {
      final long tmpThetaLong = min(unionThetaLong_, qsk_.thetaLong_);

      //count the number of valid hashes in because Alpha can have dirty values
      int numHashesIn = 0;
      TupleSketchIterator<S> it = qsk_.iterator();
      while (it.next()) { //counts valid hashes
        if (it.getHash() < tmpThetaLong) { numHashesIn++; }
      }

      if (numHashesIn == 0) {
        //numHashes == 0 && empty == false means Theta < 1.0
        //Therefore, this is a degenerate sketch: theta < 1.0, count = 0, empty = false
        result = new CompactSketch<>(null, null, tmpThetaLong, empty_);
      }

      else {
        //we know: empty == false, count > 0
        final int numHashesOut;
        final long thetaLongOut;
        if (numHashesIn > qsk_.getNominalEntries()) {
          //we need to trim hashes and need a new thetaLong
          final long[] tmpHashArr = new long[numHashesIn]; // temporary, order will be destroyed by quick select
          it = qsk_.iterator();
          int i = 0;
          while (it.next()) {
            final long hash = it.getHash();
            if (hash < tmpThetaLong) { tmpHashArr[i++] = hash; }
          }
          numHashesOut = qsk_.getNominalEntries();
          thetaLongOut = QuickSelect.select(tmpHashArr, 0, numHashesIn - 1, numHashesOut);
        } else {
          numHashesOut = numHashesIn;
          thetaLongOut = tmpThetaLong;
        }
        //now prepare the output arrays
        final long[] hashArr = new long[numHashesOut];
        final S[] summaries = Util.newSummaryArray(qsk_.getSummaryTable(), numHashesOut);
        it = qsk_.iterator();
        int i = 0;
        while (it.next()) { //select the qualifying hashes from the gadget synchronized with the summaries
          final long hash = it.getHash();
          if (hash < thetaLongOut) {
            hashArr[i] = hash;
            summaries[i] = (S) it.getSummary().copy();
            i++;
          }
        }
        result = new CompactSketch<>(hashArr, summaries, thetaLongOut, empty_);
      }
    }
    if (reset) { reset(); }
    return result;
  }