function out=legTrackerInterPeakDist(data)
%legTrackerInterPeakDists determines the distribution of intervals between
%local minima and maxima in time series data. Used in Figs S2b and 3h 
%(rows 2 and 4).
%Usage:
%out=legTrackerInterPeakDist(data)
%data = vector of ball motion or leg position time series data.

%declare temp to store inter-peak intervals as they are identified
temp=[];

%is the time series going up or down from frame 1 to 2?
if data(1)<data(2)
    upBool=1;
else
    upBool=0;
end

peakhit=0;
valleyhit=0;

%for all frames
for i=2:length(data)-1

    % if vector is going up
    if upBool==1       
        % if now going down
        if data(i)>data(i+1)
            %record peak position, switch to down mode
            peak=i;
            peakhit=1;
            upBool=0;
            
            % if peak and valley now both detected
            if peakhit==1 && valleyhit==1;
                % record interval
               temp=[temp;data(peak)-data(valley)]; 
            end
            
        end
        
    else
           
        % if now going up
        if data(i)<data(i+1)
            %record valley position, switch to up mode
            valley=i;
            valleyhit=1;
            upBool=1;
        end
    end
    
end

out=temp;