Is there a way to use inpolygon more than once ?

I am trying to use inpolygon more than once in my code, but each time when i run the program is identifying points in only one polygon.Is there a way to use inpolygon more than once ?

[KSSV]

You can use it n number of times if your polygon is different every time.

[Jan]

Yes, of course. Most likely your code conatins a bug, e.g. if you run a loop over i and use j as index of the data. If you post the relevant part of the code, we can try to find the problem.

Answer 1

[Prahlad Gowtham Katte]

Hello

We can use the inpolygon function more than once in a script file. The following code shows inpolygon being used more than once for 2 different polygons.

%Co-ordinates for 1st 
polygon
xv = [0.5;0.2;1.0;0;0.8;0.5];
yv = [1.0;0.1;0.7;0.7;0.1;1];

%Points to be checked with 1st polygon
xq = [0.1;0.5;0.9;0.2;0.4;0.5;0.5;0.9;0.6;0.8;0.7;0.2];
yq = [0.4;0.6;0.9;0.7;0.3;0.8;0.2;0.4;0.4;0.6;0.2;0.6];

%Points to be checked with 2nd polygon
xq2 = xq+1;
yq2 = yq+0.5;

%Co-ordinates for 2nd polygon
xv2=xv+1;
yv2=yv+1;

%Getting the indicators for inside and on the edge points
[on,in]=inpolygon(xq,yq,xv,yv);
[on2,in2]=inpolygon(xq,yq,xv2,yv2);

figure
plot(xv,yv) % 1st polygon
hold on
plot(xv2,yv2) % 2nd polygon

plot(xq(in&~on),yq(in&~on),'r+') % points strictly inside
plot(xq(on),yq(on),'r*') % points on edge
plot(xq(~in),yq(~in),'ro') % points outside

%2nd polygon
plot(xq2(in2&~on2),yq2(in2&~on2),'g+') % points strictly inside
plot(xq2(on2),yq2(on2),'g*') % points on edge
plot(xq2(~in2),yq2(~in2),'go') % points outside

hold off

For more information related to inpolygon please refer to the following link

Points located inside or on edge of polygonal region - MATLAB inpolygon (mathworks.com)

Hope it helps.