function avgsqi = WindowAvgSqi(sqi,tNN,HRVparams)
% avgsqi = WindowAvgSqi(sqi,tNN,HRVparams)
%
% OVERVIEW:
%
% INPUT: MANDATORY:
% sqi : Signal Quality Index
% tNN : the time indices of the rr interval data (seconds)
% HRVparams : struct of settings for hrv_toolbox analysis
%
% OUTPUT:
% avgsqi : average value of SQIs
%
% REPO:
% https://github.com/cliffordlab/PhysioNet-Cardiovascular-Signal-Toolbox
% ORIGINAL SOURCE AND AUTHORS:
% Main script written by Adriana N. Vest
% Dependent scripts written by various authors
% (see functions for details)
% COPYRIGHT (C) 2016
% LICENSE:
% This software is offered freely and without warranty under
% the GNU (v3 or later) public license. See license file for
% more information
%%
[~,col] = size(sqi);
%% Create windows for analysis of all windows
windows_all = [];
for j = 1:(floor(tNN(end))-(HRVparams.windowlength))/HRVparams.overlap
indicies = [];
try
indicies = find(tNN >= (j-1)*HRVparams.overlap & tNN < HRVparams.windowlength+(j-1)*HRVparams.overlap);
% windows_all: first coloumn is start time of sliding window
% and second column is end time of sliding window
windows_all(j,1) = tNN(indicies(1));
windows_all(j,2) = tNN(indicies(end));
catch
windows_all(j,1) = NaN;
windows_all(j,2) = NaN;
end
end
% Replace windows that aren't equal to variable windowlength (with a tolerance)
% with NaN values
meas_win_length = windows_all(:,2)-windows_all(:,1);
too_short = find(meas_win_length < (HRVparams.windowlength * (1-HRVparams.win_tol)));
for k = 1:length(too_short)
windows_all(too_short(k),1) = NaN;
windows_all(too_short(k),2) = NaN;
end
% Loop through each window of RR data
for i_win = 1:length(windows_all)
% Check window for sufficient data
if ~isnan(windows_all(i_win,1))
%idx_NN_in_win = find(tNN >= windows_all(i_win,1) & tNN < windows_all(i_win,1) + s.windowlength);
idx_sqi_win = find(sqi(:,1) >= windows_all(i_win,1) & sqi(:,1) < windows_all(i_win,1) + HRVparams.windowlength);
% Isolate data in this window
for k = 1:(col-1)
sqi_win = sqi(idx_sqi_win,k+1);
avgsqi(i_win,k) = mean(sqi_win);
end
end
end
end % end of function