function [PksAndLocsCorrected] = StepcountFunc(dataAcc_filt,StrideTimeSamples,FS); % Step count funciton extracted from other function called: Cutoff = 0.1; MinDist = floor(0.7*0.5*StrideTimeSamples); % Use StrideTimeSamples estimated above DataLFilt = dataAcc_filt; % From acceleration to Vel = cumsum(detrend(DataLFilt,'constant'))/FS; [B,A] = butter(2,Cutoff/(FS/2),'high'); Pos = cumsum(filtfilt(B,A,Vel))/FS; PosFilt = filtfilt(B,A,Pos); PosFiltVT = PosFilt(:,1); % Find minima and maxima in vertical position [PosPks,PosLocs] = findpeaks(PosFiltVT(:,1),'minpeakdistance',MinDist); [NegPks,NegLocs] = findpeaks(-PosFiltVT(:,1),'minpeakdistance',MinDist); NegPks = -NegPks; if isempty(PosPks) && isempty(NegPks) PksAndLocs = zeros(0,3); else PksAndLocs = sortrows([PosPks,PosLocs,ones(size(PosPks)) ; NegPks,NegLocs,-ones(size(NegPks))], 2); end % Correct events for two consecutive maxima or two consecutive minima Events = PksAndLocs(:,2); NewEvents = PksAndLocs(:,2); Signs = PksAndLocs(:,3); FalseEventsIX = find(diff(Signs)==0); PksAndLocsToAdd = zeros(0,3); PksAndLocsToAddNr = 0; for i=1:numel(FalseEventsIX), FIX = FalseEventsIX(i); if FIX <= 2 % remove the event NewEvents(FIX) = nan; elseif FIX >= numel(Events)-2 % remove the next event NewEvents(FIX+1) = nan; else StrideTimesWhenAdding = [Events(FIX+1)-Events(FIX-2),Events(FIX+3)-Events(FIX)]; StrideTimesWhenRemoving = Events(FIX+3)-Events(FIX-2); if max(abs(StrideTimesWhenAdding-StrideTimeSamples)) < abs(StrideTimesWhenRemoving-StrideTimeSamples) % add an event [M,IX] = min(Signs(FIX)*PosFiltVT((Events(FIX)+1):(Events(FIX+1)-1))); PksAndLocsToAddNr = PksAndLocsToAddNr+1; PksAndLocsToAdd(PksAndLocsToAddNr,:) = [M,Events(FIX)+IX,-Signs(FIX)]; else % remove an event if FIX >= 5 && FIX <= numel(Events)-5 ExpectedEvent = (Events(FIX-4)+Events(FIX+5))/2; else ExpectedEvent = (Events(FIX-2)+Events(FIX+3))/2; end if abs(Events(FIX)-ExpectedEvent) > abs(Events(FIX+1)-ExpectedEvent) NewEvents(FIX) = nan; else NewEvents(FIX+1) = nan; end end end end PksAndLocsCorrected = sortrows([PksAndLocs(~isnan(NewEvents),:);PksAndLocsToAdd],2); end