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

[Arnaud Delorme]

Dear Jonathan,

You can do that in topoplot

You can use ‘style’, ‘blank’ to removes interpolation. Then you can use ‘emarkercolor’ to change the color of each electrode dot, and ‘emarker’ to change their size. There is also an option ‘plotdisk’ to plot disk instead of dots for electrodefor 'blank’ option and the size of disk is controled by input values at each electrode.

Best wishes,

Arno

> On May 17, 2018, at 2:57 AM, Etard, Octave E <octave.etard11 at imperial.ac.uk> wrote:
> 
> 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
> 
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> 
> --
> 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
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