Extract a sphere out of a cube

Hello, I have been working with points with specific distances and angles between them, because this properties are constants I can reproduce a large bulk of points, the problem is that so far I can only generate cuboids. What I need is to extract a sphere of a cube maintaining the location of the points, the easiest way that I can think of is something like define a sphere and cut-off the points outside of it, but I have no idea how to do that, any hint is very welcome.

Thank you

Answer 1

[Michael Haderlein]

Do you mean something like this?

[X,Y,Z]=meshgrid(linspace(0,1,20),linspace(0,1,20),linspace(0,1,20));
x=X(:);y=Y(:);z=Z(:);
rem=((x-.5).^2+(y-.5).^2+(z-.5).^2)>.5^2;
x(rem)=[];y(rem)=[];z(rem)=[];
figure, scatter3(x,y,z)

[Mario]

Thank you so much, it worked perfectly!