docs: public static double sumOfProbabilities(DBIDIter ignore, DBIDArrayIter di, double[] p) {
      double s = 0;
      for(di.seek(0); di.valid(); di.advance()) {
        if(DBIDUtil.equal(ignore, di)) {
          continue;
        }
        final double v = p[di.getOffset()];
        if(!(v > 0)) {
          break;
        }
        s += v;
      }
      return s;
    }