It probably overkill to make an Analyzer script for this. All you really need is to compute the current for each case, save these numbers, and make a simple plot in Excel, GNUPlot, or whatever you prefer.
So I would just loop through the transmission spectra, compute the current, and make sure you remember which current belongs to each gate voltage and electrode potential combination (this depends on how you organized the data, so I can't advise more specifically, like if there is one NetCDF file with all gate voltages for one electrode bias, or all data collected into one huge file, or one file per gate voltage for different electrode bias).
