Border detection out of regular shape

Hi, I have this shape in the plot, but I want to detect the 4 tails sticking out of the square in order to remove them. How could I detect them? I only have a single vector of points (x,y) which are in the plot. Attached is the variable containing the points.

Thanks!

[Image Analyst]

So it's not a digital image, but a plot? That means you plotted it somehow. So just don't plot the lines. Only plot the square. You're the one who plotted it so you have complete control over what gets plotted. Or is there something I'm missing?

[Albert]

It's a plot, i just did:

% size(data) = [1000,2];
plot(data(:,1),data(:,2),'.');

Since there are a lot of points it seems there are lines but no, the supposed 'line' is a series of points that get out of the principal square. My question is that I would like to find a condition for these points so that I could remove them as:

% cond is the condition
data(cond,:)=[];

[Les Beckham]

If you attach your data as a mat file using the paperclip (either edit your question or add it in a comment), it will make it easier to help you.

[Albert]

I have attached the mat file!

Answer 1

[Matt J]

load data_points

data0=data;

shp=alphaShape(data,0.9);

[~,V]=boundaryFacets(shp);

shp=polyshape(V,'Simplify',true);

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.

for i=[-1,sqrt(2)]
shp=polybuffer(shp,i,'Joint','square');
end

tf=shp.isinterior(data);
data=data(tf,:);

plot(data0(:,1),data0(:,2),'o',data(:,1),data(:,2),'.r'); hold on

[Albert]

cool! but in the end I want another vector of points data2. Should I use inpolygon with the vertices computed and filter the data?

[Matt J]

Yes, or you could use isinterior() as in my now modified solution.

[Albert]

thanks!