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101_software/cont_area.m

+function [totalarea ca] = cont_area(C,Xgrid,Ygrid,Z_group)
+%cont_area Calculates area inside conture lines
+
+
+    % Extract the x- and y-locations from the contour matrix C.
+    ca.xL = C(1, :);
+    ca.yL = C(2, :);
+    % Interpolate on the first surface to find z-locations for the intersection
+    % line.
+    ca.zL = interp2(Xgrid, Ygrid, Z_group, ca.xL, ca.yL);
+        
+    %find curves
+    n(1) = 1;         %n: indices where the certain curves start
+    d(1) = C(2,1);  %d: distance to the next index
+    ii = 1;
+    while true
+
+           n(ii+1) = n(ii)+d(ii)+1;    %calculate index of next startpoint
+
+           if n(ii+1) > numel(ca.xL)   %breaking condition
+               n(end) = [];            %delete breaking point
+               break
+           end
+
+           d(ii+1) = ca.yL(n(ii+1));   %get next distance
+           ii = ii+1; 
+    end
+
+    %which contourlevel to calculate?
+    value = 0;             %must be member of clevels
+    sel = find(ismember(ca.xL(n),value));
+    idx = n(sel);          %indices belonging to choice
+    L = ca.yL( n(sel) );   %length of curve array
+
+    % calculate area and plot all contours of the same level
+    for ii = 1:numel(idx)
+        x{ii} = ca.xL(idx(ii)+1:idx(ii)+L(ii));
+        y{ii} = ca.yL(idx(ii)+1:idx(ii)+L(ii));
+
+        %partial areas of all contours of the same plot
+        areas(ii) = polyarea(x{ii},y{ii});   
+
+    end
+
+    % calculate total area of all contours of same level
+    totalarea = sum(areas);
+
+
+end
+