How to find whether the point lies with in the enclosed boundary region or not

Hello,

I have a set of points for which i have created a enclosed region using boundary function.

Are there some ways to find whether a point lies with in the enclosed region or not?.Please see the attached picture.for ex; if i want to know whether (x = 20 y =5) is with in the enclosed region or not.

Thanks!

Answer 1

[KSSV]

Read about inpolygon.

[HARI]

Hi,

Thanks for your quick reply.

I know about it but it doesnt give expected result in my case.please see the attahed picture.

The query point (x=20 y=20 marked in red + sign) lies not with in boundary but the output argument shows it is in(logical 1).

[Walter Roberson]

please show your code about creating the boundary and testing the point

[HARI]

Please find the code attached above.The mistake is as you can see in the above code the vertices(xv,yv) ends are not closed properly when you plot it thats why it shows logical 1.

Upon using boundary function and taking those outputs(xv(k) ,yv(k)) i get correct results.

[Simon Chan]

Vertices are not arranged in a correct order and function boundary do the job for you.

clear; clc;
load('xy.mat')
xq = 10;
yq = 10;
pgon1 = polyshape(xv,yv);

Warning: Polyshape has duplicate vertices, intersections, or other inconsistencies that may produce inaccurate or unexpected results. Input data has been modified to create a well-defined polyshape.

subplot(1,2,1)
plot(pgon1);
hold on
plot(xq,yq,'r*');
title('Use xv and yv');
subplot(1,2,2);
bd1 = boundary(xv,yv);
pgon1b = polyshape(xv(bd1),yv(bd1));
plot(pgon1b);
hold on
plot(xq,yq,'r*');
title('Use xv and yv with function boundary');

[Walter Roberson]

Nice use of polyshape(), @Simon Chan