code: public static double getScaleFactor(IAtomContainer container, double bondLength) {
          double currentAverageBondLength = getBondLengthMedian(container);
          if (currentAverageBondLength == 0 || Double.isNaN(currentAverageBondLength)) return 1;
          return bondLength / currentAverageBondLength;
      }
docs: Determines the scale factor for displaying a structure loaded from disk in a frame. An
  average of all bond length values is produced and a scale factor is determined which would
  scale the given molecule such that its See comment for center(IAtomContainer atomCon,
  Dimension areaDim, HashMap renderingCoordinates) for details on coordinate sets
  
  @param container  The AtomContainer for which the ScaleFactor is to be calculated
  @param bondLength The target bond length
  @return The ScaleFactor with which the AtomContainer must be scaled to have the target bond
  length