In the chemical data that we process, there are often two different ways to present the x-axis data. For instance, think of energy/wavelength, diffraction angle/length scale, or even simpler speed in mph/speed in kph.
These two sets of parameters have an obvious relationship to each other, that in most cases is not linear as in energy ~ 1/wavelength or d ~ 1/sin(theta).
A good example is this graph, where the authors have presented both wavelength and energy on the top and bottom x-axes.
How could I do this in R/ggplot2?
(note: my apologies. As this is my first question, I can't post images yet)