Parsing .s2p data through an automation script to plot graphs of the various s-parameters
I found this neat MATLAB S-Parameter toolbox. 

Using the SXPParse.m function we will get the data of the s-parameters in the .sNp file in terms of real and imaginary parts. 

If you just want to keep it in its given format, then change the function such that it return raw_data instead of data. 

Using the link that gave us information of the format of the file we can no easily create automation scripts to extract the gain and phase of the s-parameters. 

Here is a sample of the code:

DataFileName = 'cpl iso.s2p';
[freq, raw_data,data, freq_noise, data_noise, Zo] = SXPParse(DataFileName);

% interested s-parameters data
interested_data = raw_data(301:401,:); %dB and angle (degrees)
interested_freq = freq(301:401); %Hz

%Magnitude
subplot(2,1,1)
plot(interested_freq,interested_data(:,3),'-r');
hold on
plot(interested_freq,interested_data(:,5),'-b');
legend('S21','S12');
xlabel('Frequency (Hz)','fontsize',12,'fontweight','b')
ylabel ('Amplitude (dB)','fontsize',12,'fontweight','b')
title ('1 - CPL, 2 - ISO','fontsize',16,'fontweight','b')