How do I identify points within a user defined shape?

Hi all,

I have the folliwing code:

% genertae random data
%initial parameters
npoints= 300;
xrange = [0 100];
yrange = [0 100];

% generating randomly placed points
points = rand(npoints, 2);

% normalizing the xy locations according to the parameters
points(:,1) = points(:,1)*diff(xrange) + xrange(1);
points(:,2) = points(:,2)*diff(yrange) + yrange(1);

%plot
figure(2), clf
plot(points(:,1),points(:,2), 'b+','linewidth',2, 'markersize',12);
hold on

n=5;
a=zeros(n,1);
b=zeros(n,1);
for i=1:5
    [x,y] = ginput(1);       % these 5 points can be used to make any kind of shape (preferable small in size) on the plot
     h1 = text(x,y,int2str(i), ...
                'HorizontalAlignment','center', ...
                'Color', [1 0 0], ...
                'FontSize',8);
    a(i)=x;
    b(i)=y;
end

%plotting a line between all points
plot([a ; a(1)],[b ; b(1)], 'b-');
hold off

% references:
% https://www.youtube.com/watch?v=9C-MLBZ6u0Q
% https://www.mathworks.com/matlabcentral/answers/1812505-how-to-show-selected-points-and-connect-first-point-to-last-point?s_tid=prof_contriblnk

I want to find a way to identify all those points that lie within a user defined shape. A few examples of user defined shapes would be like:

I will appreciate if someone can kindly help me out. Thanks!

Answer 1

[David Hill]

Look at polyshape and isinterior

[Mariam Shahab]

Thank you for your help. I was able to use both functions to identify the points. Just one question; how do I plot the identified points using the TFin array?

[David Hill]

x=10*rand(1,1000);
y=10*rand(1,1000);
p=polyshape([2 5 5 2],[2 2 6 2]);
figure;
hold on;
idx=isinterior(p,x',y');
scatter(x(idx),y(idx),10,'red','filled');
scatter(x(~idx),y(~idx),10,'blue','filled')
plot(p)