create simple time window

Dear all,

it seems to be simple but I don't get it. I wrote a script to get a synchronization index for a 7 minute walk:

%% compute the phase angle difference

for i = 1:numel (data_trimmed_al)
    data_trimmed_al(i).phase_angle = angle (data_trimmed_al(i).hilbertx_hinweg_norm);
    data_trimmed_al(i).phase_angle_difference = (data_trimmed_al(i).phase_angle (:,1) - data_trimmed_al(i).phase_angle (:,2));
end 
 
% Euler representation of phase angle difference

for i = 1:numel (data_trimmed_al)
    data_trimmed_al(i).euler_phase_angle_difference = exp (1i * data_trimmed_al(i).phase_angle_difference);
end
 
% mean vector (in complex space)

for i = 1:numel (data_trimmed_al)
    data_trimmed_al(i).mean_vector_complex = mean (data_trimmed_al(i).euler_phase_angle_difference);
end 

% ISPC (Synchronization Index)

for i = 1:numel (data_trimmed_al)
    
% here I would like to insert a loop to calculate the index every 10
% seconds instead of the whole data set. 

    data_trimmed_al(i).ISPC_together = abs (data_trimmed_al(i).mean_vector_complex);
end

Now, I wan't to calculate the index for every 10 seconds instead of the whole walk of seven minutes.

Do you have any suggestions or advice? I can't find any solutions for my problem.

Regards, Jonas

[Harald]

Hi Jonas,

I at least fail to understand what needs to be done.

It is not clear to me from the code how it relates to 7 minutes, let alone how to modify it to relate to 10 seconds.

If you can share data and some additional explanation, that might help.

Best wishes,

Harald

Answer 1

[Mahmoud]

Hi Jonas,

If I understood you correctly you are trying to calculate the Inter-Site Phase Clustering (ISPC) for a 7-minute walk. Currently, your script calculates the ISPC for the entire 7-minute duration. However, you want to modify your script to calculate the ISPC for every 10-second interval during the walk.

To do that I would suggest introducing an additional loop in your script that iterates over the data in 10-second intervals. The exact implementation depends on the sampling rate of the data. Assuming that the data is sampled at a rate of Fs samples per second, a 10-second interval would contain 10*Fs samples.

Fs = ...; % Sampling rate in samples per second
interval = 10 * Fs; % Number of samples in 10 seconds

% Get total number of samples
total_samples = length(data_trimmed_al(1).phase_angle_difference);

% Calculate total number of intervals
total_intervals = floor(total_samples / interval);

for i = 1:numel(data_trimmed_al)
    % Preallocate array for ISPC values
    data_trimmed_al(i).ISPC_together = zeros(total_intervals, 1);
    
    for j = 1:total_intervals
        % Get start and end indices for this interval
        start_idx = (j-1)*interval + 1;
        end_idx = j*interval;
        
        % Calculate mean vector for this interval
        mean_vector_complex = mean(data_trimmed_al(i).euler_phase_angle_difference(start_idx:end_idx));
        
        % Calculate ISPC for this interval
        data_trimmed_al(i).ISPC_together(j) = abs(mean_vector_complex);
    end
end