function out=legTrackerPrepCorrs(data,windowSize)
%legTrackerPrepCorrs takes instrument data and returns the pairwise
%correlation coefficients between data vectors within a sliding window.
%Padded by zeros. Evaluated in Figure 2d, but NOT USED for the final
%classification protocol in Kain et al.
%Usage:
%out=legTrackerPrepCorrs(data,windowSize)
%data = raw data from instrument.
%windowSize = 1/2 length of sliding window for calculating local
%     correlation coefficients

%allocate space in memory for output
numFrames=size(data,1);
temp=zeros(size(data,1),66);

%constant for which coordinates of cross-correlation matrix to retain
triangle=triu(ones(12,12),1);
triangle=triangle(:);

%for all frames, excluding those when the window overflows
for i=windowSize+1:numFrames-windowSize
    
    %pairwise correlations between data vectors in each window
    corrs=corr(data(i-windowSize:i+windowSize,1:12));
    
    %take 1 per pair.
    corrs=corrs(:);
    corrs=corrs(triangle==1);
    temp(i,:)=corrs';
end

%replace nans with 0s and output
temp(isnan(temp))=0;
out=temp;