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