[Eeglablist] Topoplot: can it just plot the electrode values and not interpolate them?

[Etard, Octave E]

Dear Jonathan,

I played with this some time ago. For basic use cases, the code below should work. Adjust to display the required colours.

Best wishes,

Octave

% ------
% coordinates from the topoplot function
[y,x] = pol2cart(pi*[EEG.chanlocs(:).theta]/180,[EEG.chanlocs(:).radius]);

Rd = max([EEG.chanlocs(:).radius]);
plotrad = min(1.0,max(Rd)*1.02);
plotrad = max(plotrad,0.5);

x =  x * 0.5 / plotrad;
y =  y * 0.5 / plotrad;
h = 2.1;

figure;
topoplot([],EEG.chanlocs);
hold on;
% adjust colours to display the data you want
plot3(x,y,h*ones(size(x)),'o','Markersize',10,'MarkerEdgeColor','none','MarkerFaceColor','r');
% ------

________________________________________
From: eeglablist <eeglablist-bounces at sccn.ucsd.edu> on behalf of Scott Makeig <smakeig at ucsd.edu>
Sent: 16 May 2018 01:12:26
To: Jonathan Kane
Cc: eeglablist at sccn.ucsd.edu
Subject: Re: [Eeglablist] Topoplot: can it just plot the electrode values and not interpolate them?

Jonathan -  No, we never thought of plotting channel values as colored discs. It should not be too hard to go into the topoplot code and look for plotting commands... etc. But a programming chore, for sure ...

Scott

On Fri, Jul 7, 2017 at 12:08 PM, Jonathan Kane <jakane007 at gmail.com<mailto:jakane007 at gmail.com>> wrote:
Hello,
   I am worried about interpolation artifacts in topoplot.  I therefore want to plot the value at each electrode location as a colored and filled circle (where the color corresponds to the value at the electrode), and not interpolate between them.  I can't seem to find an option in topoplot to do that.  It CAN plot the locations of the electrodes using the 'style' - 'blank' combination along with the 'emarker' option, but it can't plot different electrode values as corresponding colors.

I tried a second approach:  Since what I essentially want to do is plot the electrode values as a scatter plot, I tried to overlay a scatter.m plot on top of the head outline given by topoplot.  I used the X, Y information in EEG.chanlocs as the coordinates, but it seems that both of the X and Y limits on the topoplot have been set to [-0.5250 0.5250] (i.e., it doesn't seem to use the actual X, Y locations of the electrodes, but transforms them onto a different grid).  Any idea how that is done so that I can do the coordinate transformation myself and then use scatter.m?

Thanks!

Jonathan

_______________________________________________
Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
To unsubscribe, send an empty email to eeglablist-unsubscribe at sccn.ucsd.edu<mailto:eeglablist-unsubscribe at sccn.ucsd.edu>
For digest mode, send an email with the subject "set digest mime" to eeglablist-request at sccn.ucsd.edu<mailto:eeglablist-request at sccn.ucsd.edu>



--
Scott Makeig, Research Scientist and Director, Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla CA 92093-0961, http://sccn.ucsd.edu/~scott