How can I represent points and lines in 3 dimensions?

ox=0; oy =0; oz=0;

x1=0; y1 =0; z1=0;

x2=0; y2 =0; z2=0;

x3=2; y3 =0.6; z3=0;

x4=2; y4 =0.3; z4=0;

x5=2; y5 =0.3; z5=-0.7;

x6=2; y6 =0.3; z6=-0.7;

hold on;

x = [ox x1 x2 x3 x4 x5 x6]; % a matrix of dots

y = [oy y1 y2 y3 y4 y5 y6];

z = [oz z1 z2 z3 z4 z5 z6];

plot3(x,y,z,'ok') %plot points on a graph

plot3([ox, x1],[oy, y1],[oz, z1], 'r') %to connect dots and lines

plot3([x1, x2],[y1, y2],[z1, z2], 'g')

plot3([x2, x3],[y2, y3],[z2, z3], 'b')

plot3([x3, x4],[y3, y4],[z3, z4], 'c')

plot3([x4, x5],[y4, y5],[z4, z5], 'm')

plot3([x5, x6],[y5, y6],[z5, z6], 'y')

grid

max_L = 3;

axis([-max_L max_L -max_L max_L -max_L max_L]);

If I draw like this, it will appear in 2D instead of 3D. How can I represent it in 3D?

Answer 1

[DGM]

Either move the hold on statement after the first call to plot3(), or issue a

view(3)

command after plotting.

Creating a pile of named variables only leads to problems. Imagine if you wanted to do this with 100 points. With the following example, the code doesn't have to be scaled with the number of points. All you need to do is generate a new colormap of the appropriate length.

% just the points
x = [0 0 0 2 2 2 2];
y = [0 0 0 0.6 0.3 0.3 0.3];
z = [0 0 0 0 0 -0.7 -0.7];

plot3(x,y,z,'ok') %plot points on a graph
hold on;

% rearrange into a series of segments
x = repelem(x,1,2); 
x = reshape(x(2:end-1),2,[]).';
y = repelem(y,1,2); 
y = reshape(y(2:end-1),2,[]).';
z = repelem(z,1,2); 
z = reshape(z(2:end-1),2,[]).';

plot3(x,y,z) %to connect dots and lines

% apply whatever colormap you want to the series of line segments
cmap = hsv(6);
cmap = cmap([1 3 5 4 6 2],:); % to get the same order you used
set(gca,'colororder',cmap)

grid
max_L = 3;  
axis([-max_L max_L -max_L max_L -max_L max_L]);

[종수 허]

Thanks, I solved the problem. Thank you so much !!!

[종수 허]

Have you ever wondered why you would use repelem and reshape?

[DGM]

Consider the example:

x = 1:10

x = 1×10

1 2 3 4 5 6 7 8 9 10

x = repelem(x,1,2); 
x = reshape(x(2:end-1),2,[]).'

x = 9×2

1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10

Each row becomes a line object.

[종수 허]

thank you. My question has been resolved !!!!

Answer 2

[KSSV]

It is in 3D, you need to change the view.

view(3)