Exclude some nodes from a 3D point cloud (select only neighboring nodes)

Hi! I would need code to create a matrix of nodes excluding those circled in red. Is there any code that I could use?

I would need a code where, for example, I select a node I am interested in and it automatically selects all neighboring nodes (within a certain distance x,y,z).

selection = importdata("selection.mat");

figure
plot3(selection(:,1),selection(:,2),selection(:,3),'b.','Markersize',5)
grid on
hold on
axis equal
xlabel('x')
ylabel('y')
zlabel('z')

Answer 1

[Matt J]

X=load('selection').selection; %shorten data name

G=graph(pdist2(X,X)<=10);

T=conncomp(G);

[~,i]=max(histcounts(T,[unique(T),inf]));

I=T==i;

plot3(X(I,1),X(I,2),X(I,3),'b.','Markersize',5); hold on
plot3(X(~I,1),X(~I,2),X(~I,3),'r.','Markersize',5); hold off
grid on
axis equal
xlabel('x'),ylabel('y'),zlabel('z')