[Eeglablist] plot of components spectra and maps

[Makoto Miyakoshi]

Dear Ida,

Ok, you should use the option 'freqfac'.
Follow the steps shown below.
1. type 'edit' to open empty editor
2. run the pop_spectopo from GUI
3. type 'eegh' to get the log of the last command
4. copy the pop_spectopo line of the log and paste it to empty editor.
5. add this at the beginning:
       [spectra,freqs,speccomp,contrib,specstd] = pop_spectopo(...
6. add 'freqfac', 64 at the end of the line
7. select all lines in the editor and press F9
8. open 'freqs' in the workspace. You should see a frequency
resolution of (0 to your nyquist)/16385 there.

Let's say your sampling rate is 250Hz, and you are interested in
10.1Hz spectrum and its map. Then, 10.1 is between 10.0937 and
10.1013, and I think the latter is use for plotting.

Makoto

2012/6/9 ida miokovic <ida.miokovic at gmail.com>:
> I just came to conclusion that these frequencies are rounded to the nearest
> value (0Hz, 0.5Hz, 1Hz) when plotting, am I right?
>
> Are they rounded in calculations also or a specified value is used? Is there
> a way for me to work with the actual frequency I want? How could I call this
> function as a code? I tried following:
>
> pop_spectopo('EEG',[-2000 1000],100,0.33)
>
> for current EEG data set, specified range, 100% of the data and 0.33 Hz as a
> frequency of interest, but something is not OK and I get following error:
>
> ??? Attempt to reference field of non-structure array.
>
> Error in ==> pop_spectopo at 120
> if ~isempty(EEG.chanlocs)
>
> Thank you very much for any help.
>
> Ida
>
>
> On Sat, Jun 9, 2012 at 3:15 PM, ida miokovic <ida.miokovic at gmail.com> wrote:
>>
>> Hello,
>>
>> I have question regarding procedure: Plot --> Components spectra and maps.
>> I am interested in channel with the maximum power at the specified frequency
>> so I put brackets [] in the electrode number to analyze and I use 100% of
>> the data.
>>
>> Frequency of my interest is for example 0.27 Hz, but when the calculation
>> is done, on the plot I get the scalps (components activities) connected to
>> the frequency around 0.45 Hz (plotting frequency range was 0 1). Same
>> happens for the frequency 0.25 Hz (on the plot I get 0.45 Hz). On the other
>> side, plot of the 1Hz is OK. In the workspace it is using value I put in the
>> GUI, but on  the plot in case of 0.25, 0.27, 0.3, the frequencies are not
>> those from the GUI.
>>
>> To me, it is important to get the channel of my interest and the
>> components where there is the most of specified frequencies. If it is just
>> plotting issue, I don't mind, but any hints why does it happen would be
>> great. Maybe it is working better with integer values of frequencies...
>>
>> Thanks
>>
>> Ida
>
>
>
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-- 
Makoto Miyakoshi
JSPS Postdoctral Fellow for Research Abroad
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego