[Eeglablist] Plotting single channels

[Stefan Debener]

Hi Adrian,

You could do this easily from commandline  - if you know where to find 
your data. EEG.data is (after epoching!) a  3-D matrix: Channels x 
Frames x Trials. Thus, averaging over the third dimension gives you the 
ERP. For plotting the ERP of a specific channel just enter the channel 
index, e.g., for channel 12, erp = mean(EEG.data(12,:,:),3); For 
comparing two or more conditions (or subjects), you need to load the 
single-condition datasets first. Let's assume the first loaded dataset 
is condition A and the second refers to condition B. You have access to 
these single datasets via ALLEEG, that is, ALLEEG(idx).data:

erpa = mean(ALLEEG(1).data(12,:,:),3);
erpb = mean(ALLEEG(2).data(12,:,:),3);
figure;
hold on;
plot(EEG.times,erpa, 'b');
plot(EEG.times,erpb, 'r');
set(gca, 'Ydir', 'reverse');
title('ERP at channel 12');

Play a bit with the code and you will soon be able to improve it. E.g., 
interesteing information could be added to the plot, such as the number 
of trials for each condition (into the title), difference ERPs, or 
odd/even split averages to asses the SNR...


Hope this helps,
Stefan





. The code below retunrs the

Adrian Willoughby wrote:
> Hi,
>  
> I'm having a hard time plotting single channels ERPs for two different 
> conditions from the command line.
>  
> I can get all the channels plotted in the scalp array easily enough 
> using the pop_comperp command.  But I can't seem to be able to do the 
> equivalent of clicking on one of the plots and having it open up in a 
> new window from the command line.  I've managed to find the copyaxis 
> function that will open up a new window and display the axes.  Does 
> anyone know how to get the actual waveforms displayed there as well?  
> Or an alternative method for plotting two conditions (datasets) at one 
> channel?  Thanks,
>  
> Adrian
>  
>  
> ------------------------------------------------------------------------
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