How to calculate the perimeter of a polygon without using built-in function in matlab

clear;clc;
P = [1 1 ;1 2; 2 1 ; 3 1 ;3 5 ; 4 2 ; 4 3 ; 4 4 ;  2 4 ; 1 4 ; 1 3 ];%the original is not in order (random)
% How to calcute the perimeter of boundary from this 2D data?

[madhan ravi]

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Answer 1

[ha ha]

clear;clc;
P = [1 1 ;1 2; 2 1 ; 3 1 ;3 5 ; 4 2 ; 4 3 ; 4 4 ;  2 4 ; 1 4 ; 1 3 ];%the original is not in order (random)
hold on;scatter(P(:,1),P(:,2),31,'.k');xlim ([0 7]);ylim ([0 7]);%plot data
x=P(:,1);y=P(:,2);
k = boundary(x,y,1);
X=x(k);
Y=y(k);
plot(X,Y);
points=[X Y];%point in sequence order to compute the perimeter
perimeter = 0;
for i = 1:size(points, 1)-1
perimeter = perimeter + norm(points(i, :) - points(i+1, :));
end
perimeter = perimeter + norm(points(end, :) - points(1, :)); % Last point to first